This effort was sponsored by the Naval Meteorology and Oceanography Command. In April 1995, NRL Meteorologist CDR R. G. Handlers, USN; LT J. Roth, USN, Officer in Charge, NPMOD Whidbey Island; and SAIC Meteorologist Mr. R. D. Gilmore met with the following persons to obtain much of the background information contained in this evaluation: BMCM Norman Kempf, USN and Captain Lorene Grant, SUBBASE Bangor Harbor Pilots; BM1 Hockenberry, USN, NUWES Keyport; Mr. R. D. Bronson, Ship Berthing Officer, and Harbor Pilots Captain John Ryland and Captain Bill Rice, PSNS Bremerton; LCDR Parker, USN and EN1 Stazel, USN, Indian Island Naval Ordnance Station; LT Ron Moore, USN, Port Operations Officer and ENC M. Halvorson, USN, Service Craft Division CPO, NAVSTA Everett; Mr. David Schneidler, Manager, Customer Services, Marine Division, Port of Seattle; Captain Bert Holmes, President of the Puget Sound Pilot Association; Mr. Dave Williams, Harbor Master, Oak Harbor Marina; Dr. Bradley Colman, Science and Operations Officer and Mr. H. E. (Ted) Buehner, Warning Coordination Meteorologist of NOAA's National Weather Service Forecast Office at Sand Point in Seattle; and Professors Cliff Mass and Mark Albright of the University of Washington's Environmental Sciences Department. In addition, Mr. Jim Jones, Mr. Bill Burton and Mr. Pat Brandow of NOAA’s National Weather Service Office at Sand Point; Mr. Sid Stillwaugh, Pacific NW Liaison Officer, National Oceanographic Data Center in Seattle; and BM1 R. Reed, USCG of the United States Coast Guard Station, Port Angeles provided valuable support and information during the preparation of this evaluation. Additionally, LT John Williams, USN, relieving Port Operations Officer at NAVSTA Everett, provided pertinent follow-up information about NAVSTA Everett subsequent to the April 1995 visit.

SUMMARY

This handbook was developed to provide a concise guide, oriented toward the ship captain, for specific port and harbor locations in Puget Sound, to aid in decision making during periods of adverse weather.

Puget Sound is located in northwest Washington State. The Sound extends approximately 70 nmi southward from the eastern end of the Strait of Juan de Fuca, the primary oceanic access to the Sound. The Strait is an 80 nmi long narrow body of water extending east-west between Vancouver Island and the Olympic Peninsula. Because of the considerable distance that must be traveled to reach the open sea, evasion at sea to avoid heavy weather is not a practical option for ships moored in Puget Sound. Under most severe weather scenarios, moored vessels can avoid damage by doubling and tending mooring lines during the strongest winds.

Several harbor facilities of interest to the U.S. Navy are located in the Puget Sound area. The facilities include Naval Station, Everett; Puget Sound Naval Shipyard, Bremerton; Naval Submarine Base, Bangor; Naval Undersea Weapons Engineering Station, Keyport; Naval Ammunition Depot, Indian Island; Naval Air Station, Whidbey Island’s Seaplane Base Pier; the Port of Seattle; and the Port of Tacoma.

Puget Sound is located in an area of complex geography and topography. The central part of the Sound is bordered on the west by the Olympic Mountains and to the east by the Cascade Mountains. The two mountain ranges create a relatively narrow channel for southerly/northerly winds as they move through the area. Strong southerly winds are common over Puget Sound during late autumn, winter and early spring. The most severe wind conditions are associated with fronts and low pressure systems approaching from the Pacific Ocean.

The effect of strong winds across the Puget Sound region varies greatly from location to location. Wind conditions that may adversely affect one area of the Sound may have little or no effect on another. Many of the sites addressed in this evaluation are located immediately adjacent to significant topographic features that either shield the port from strong winds or enhance wind flow at that location.

1.0 DESCRIPTION OF PUGET SOUND REGION

Puget Sound is located in northwestern Washington state (Figure 1). The water area that lies between the Olympic Peninsula in the extreme northwestern part of Washington state, British Columbia's Vancouver Island, and western Washington state between the city of Olympia and the Canadian Border is a prominent feature of northwest Washington. This entire body of water is often erroneously referred to as Puget Sound. Instead, it is actually comprised of several separate and distinct water areas, including the Strait of Juan de Fuca, the Strait of Georgia, the water area surrounding the San Juan Islands, Hood Canal, and Puget Sound. Puget Sound is the main focus of this evaluation, although some adjoining waters are also addressed. The Strait of Georgia and the water area surrounding the San Juan Islands do not abut on Puget Sound and are outside the scope of this evaluation.

Figure 1. Puget Sound’s location in western Washington.

1.1 STRAIT OF JUAN DE FUCA

The Strait of Juan de Fuca is an 80 nmi long, narrow body of water that passes between Vancouver Island and the north end of Washington state's Olympic Peninsula (Figure 1).

It serves as the primary oceanic access to Puget Sound. The Strait of Juan de Fuca is approximately 12 nmi (22 km) wide from its western entrance on the Pacific Ocean eastward for approximately 50 nmi (93 km), where it widens to about 16 nmi (30 km). Its eastern limit is the west coast of Whidbey Island. The rugged terrain on the north and south sides of the Strait is heavily wooded, rising rapidly to elevations of considerable height (U.S. Department of Commerce, 1992).

1.2 PUGET SOUND

Puget Sound, a bay with numerous channels and branches, extends approximately 70 nmi (130 km) south from the eastern end of the Strait of Juan de Fuca to the city of Olympia (Figure 1). Puget Sound includes the water area south of a line from the northeast part of the Olympic Peninsula to the western extremity of Whidbey Island, thence eastward from the north end of Whidbey Island.

Several ports and harbors are located on Puget Sound, including the major U.S. Navy installations of Naval Station, Everett and Puget Sound Naval Shipyard, Bremerton (Figure 2). Naval Submarine Base, Bangor is located on the adjacent Hood Canal. Maritime traffic on Puget Sound is heavy; many large commercial vessels using the Ports of Everett, Seattle, Tacoma and others, enter and depart Puget Sound each day. Additional traffic on the Sound is created by the frequent runs of large Washington State vehicle and passenger ferries as they cross the Sound on generally east-west traffic routes that are perpendicular to normal inbound and outbound maritime traffic channels. Additionally, many recreational and commercial small craft operate throughout the Puget Sound and adjacent waters.

Figure 2. Locations in Puget Sound of interest to the U.S. Navy.

1.3 ADMIRALTY INLET

Admiralty Inlet is a narrow body of water passing between Whidbey Island on the east and the northeast part of the Olympic Peninsula on the west (Figure 2). Included within the limits of Puget Sound, Admiralty Inlet begins at the east end of the Strait of Juan de Fuca and extends southward along the west coast of Whidbey Island for approximately 15 nmi (29 km). All deep draft vessels entering or leaving Puget Sound must pass through Admiralty Inlet. Consequently, it is a busy traffic area for large vessels. A Washington State ferry operates on a regular run between Port Townsend and the west shore of Whidbey Island. The ferry’s route is perpendicular to the inbound and outbound maritime traffic routes near the north end of Admiralty Inlet.

Topography adjacent to Admiralty Inlet is sufficiently high to create a channel for surface winds. Strong southeasterly winds are common during late autumn, winter and early spring.

1.4 HOOD CANAL

Hood Canal is a long, narrow body of water that extends southwestward near the southern end of Admiralty Inlet (Figure 2). Approximately 55 nmi (102 km) long, Hood Canal extends southwestward for approximately 44 nmi (81 km) from Admiralty Inlet before turning sharply east northeastward for another 11 nmi (20 km) where it ends in tidal flats. A floating bridge crosses Hood Canal approximately five nmi (nine km) southwest of its mouth. Submarines and other vessels going to/from Puget Sound and Naval Submarine Base, Bangor must pass through a 600 ft (183 m) wide passage that is created by retracting floating pontoon sections located near the center of the bridge.

Topography immediately adjacent to Hood Canal commonly exceeds 400 ft (122 m). Because of funneling effects, Hood Canal experiences strong southwesterly winds during periods of synoptic scale southerly flow.

1.5 SARATOGA PASSAGE

Saratoga Passage lies between Whidbey Island and Camano Island (Figure 2). From its south end, it extends northwestward approximately 18 nmi to Crescent Harbor on Whidbey Island, and then turns eastward to the waters of Skagit Bay, just north of Camano Island. Depths in Saratoga Passage vary from 600 ft at its south end to approximately 90 ft at the entrance to Crescent Harbor (U.S. Department of Commerce, 1992). Elevations on both sides of Saratoga Passage exceed 200 ft for most of its length. Some rises on Camano Island exceed 400 ft. Because of the adjacent topography, the southeasterly winds commonly occurring during late autumn, winter and early spring are funneled and accelerated as they pass through Saratoga Passage.

2.0 TOPOGRAPHY OF THE REGION

The topography surrounding the Puget Sound region is mountainous and rugged (Figure 3). The main portion of the north-south oriented Cascade Mountain Range lies approximately 70 to 80 nmi (130 to 148 km) east of Puget Sound. The foothills of the range begin only a few miles east of the Sound. Elevations commonly exceed 6,000 ft (1,829 m) over much of its range, with some peaks exceeding 8,000 ft (2,438 m). Two prominent mountains are visible in good weather from Puget Sound waters. Mount Rainier, the highest peak in Washington State, is located approximately 40 nmi southeast of Tacoma. With an elevation of 14,410 ft (4,392 m), Mount Rainier is a prominent feature of the landscape. Mount Baker, with an elevation of 10,778 ft (3,285 m), can be seen northeast of Puget Sound. It is located approximately 45 nmi (83 km) northeast of Whidbey Island. Mount Rainier and Mount Baker are of volcanic origin and each is roughly conical in shape.

Figure 3. Topography of northwest Washington state and southwest British Columbia, including Vancouver Island.

Elevations in feet. Adapted from Overland and Walter (1981).

The Olympic Peninsula, which lies west of Puget Sound, is dominated by the Olympic Mountains. Elevations in the Olympics commonly exceed 5,000 ft (1,524 m). With an elevation of 7,965 ft (2,428 m), Mount Olympus is the highest peak in the range. The Olympic Mountain Range is roughly circular in shape, with an average diameter of approximately 40 nmi (74 km).

The Coastal Range dominates most of the extent of Vancouver Island, which lies north of the Strait of Juan de Fuca. Elevations on the southeast-northwest oriented island exceed 7,000 ft (2,134 m) near its approximate mid-point. The highest point adjacent to the Strait of Juan de Fuca is a 3,686 ft (1,123 m) peak.

Outside of the mountain ranges discussed above, the terrain adjacent to Puget Sound is, for the most part, less than 1,000 ft (305 m) in elevation. Much of the land is low-lying, with an extensive network of rivers, estuaries and tidal marshes. As previously mentioned, terrain in two areas of interest to this evaluation causes localized wind effects due to funneling. The topography adjacent to Admiralty Inlet is sufficiently high to create a channel for surface winds. Southeasterly winds are amplified as they funnel through the Inlet, with resulting strong winds being common during autumn, winter and spring months. A second area subject to funneling is Hood Canal. Topography immediately adjacent to Hood Canal commonly exceeds 400 ft (122 m). The Olympic Mountain Range, with elevations over 7,000 ft (2,134 m), lies a few miles west of Hood Canal. Because of funneling effects of the significant elevations on both sides of the waterway, Hood Canal often experiences strong southwesterly winds during periods of synoptic scale southerly flow in advance of approaching low-pressure systems.

3.0 GENERAL ENVIRONMENTAL CONDITIONS IN THE PUGET SOUND REGION.

The following is a general discussion of general environmental conditions experienced in the Puget Sound region. The reader is referred to Section 4 and Appendix A for additional, more detailed, discussions of specific phenomena.

3.1 WIND

The Puget Sound region experiences two primary wind regimes. The most significant occurs in late autumn, winter, and early spring, when southerly winds prevail. Most of the southerly winds occur in advance of approaching low pressure/frontal systems moving eastward across the Pacific Ocean. The winds are experienced as south-southwesterly at the south end of Puget Sound, southerly in the central Sound, and southeasterly in northern Puget Sound. Sustained winds of small craft velocity (20-33 kt) are commonly experienced. Gale velocities (34-47 kt) may occur in advance of the stronger low pressure/frontal systems. Storm force (³48 kt) winds are only rarely observed.

The second wind regime occurs in late spring, summer, and early autumn when vigorous transient extratropical low pressure systems are uncommon. The prevailing direction in central and southern Puget Sound is still south to southwesterly, but velocities are reduced to an average of seven to eight kt. The prevailing wind at Whidbey Island, at the east end of the Strait of Juan de Fuca, is westerly five to seven kt. Nighttime and early morning winds throughout the Puget Sound region are mostly light and variable.

An additional high wind event occurs occasionally during the winter season when a very intense cold front (referred to as an Arctic front) moves southward into northern Washington State. The debate of terminology, Arctic or polar continental front/air mass, is long standing (see discussion in Chapter 4 of Palmen and Newton (1969)). In this guide the general usage will be polar continental, but when there are direct extractions from referenced material that uses the term Arctic (as in Appendix A), it will not be changed. When the cold continental polar air mass behind the front reaches southern British Columbia, it flows southwestward through the Fraser River Valley and accelerates toward Bellingham (Figure 1). Gale force (34-47 kt) northeasterly winds at Bellingham and very cold temperatures are not uncommon with such an event. The cold air then normally flows southwestward across the San Juan Islands toward the north shore of the Olympic Peninsula. Although the frontal systems occasionally move southward through the entire Puget Sound area, the strong winds associated with the passage of these fronts are seldom experienced south of Whidbey Island.

3.2 WAVES

Wave motion in the waters of Puget Sound is limited by the complex shape of the geography of the Puget Sound basin. Straight line distances are relatively short, so wave generation is restricted due to lack of fetch. In general, wave heights in most of Puget Sound are limited to approximately six ft with gale force winds (34-47 kt). The Strait of Juan de Fuca does not have the fetch limit restriction for east-southeasterly and west-northwesterly winds, however. Wave motion at the mid-point of the Strait can exceed 15 ft for some direction, wind speed and duration combinations.

When strong westerly flow prevails over Puget Sound, waves moving eastward through the Strait of Juan de Fuca enter the north part of Admiralty Inlet, creating the largest waves in Puget Sound. The waves are the most hazardous when they coincide with a strong, north-flowing ebb current in Admiralty Inlet. Mariners transiting Admiralty Inlet should be aware of the potential for excessive wave motion in the area.

3.3 TIDES

There is considerable variation in tide levels in Puget Sound, Hood Canal, Saratoga Passage and the Strait of Juan de Fuca. The entire Puget Sound region, including the Strait of Juan de Fuca experiences a semi-diurnal tide cycle, with two high tides and two low tides commonly occurring during an approximate 25 hour period. At Everett, in the northern part of Puget Sound, the normal diurnal tidal range is approximately 11.1 ft, with an extreme range of 19 ft (-4.5 ft to +14.5 ft). At the Port of Seattle in the central part of the Sound, the normal diurnal tidal range is approximately 11.4 ft, but can range as high as 18 ft (U.S. Department of Commerce, 1992). The normal diurnal range at Bremerton in the central part of the Sound is approximately 11.7 ft, with a maximum range of approximately 16 ft. In Hood Canal, the normal diurnal tidal range is approximately 11.1 ft, but it can range as high as 16 ft. Table 1 presents average conditions existing at or near the listed sites and is intended for general information only. The use of up-to-date tide tables is strongly recommended.

Table 1. Tidal data for various locations on the Strait of Juan de Fuca, Puget Sound, Hood Canal and Saratoga Passage. Adapted from U. S. Department of Commerce (1992), DMAHTC (1993), and locally produced tidal tables. Data are rounded to nearest 1/10th of a foot (meter).

LOCATION	MEAN RANGE FT (M)	DIURNAL RANGE FT (M)	MEAN TIDEFT (M)
West end of the Strait of Juan de Fuca (Neah Bay)	5.5 (1.7)	7.9 (2.4)	4.3 (1.3)
East end of the Strait of Juan de Fuca (Discovery Bay)	4.8 (1.5)	7.9 (2.4)	4.8 (1.5)
Indian Island /Port Townsend	5.2 (1.6)	8.4 (2.6)	5.1 (1.6)
Keyport/Port Orchard	8.4 (2.6)	11.8 (3.6)	6.9 (2.1)
Everett	7.5 (2.3)	11.1 (3.4)	6.5 (2.0)
Seattle/Elliott Bay	7.7 (2.3)	11.4 (3.5)	6.7 (2.0)
Bremerton/Sinclair Inlet	8.4 (2.6)	11.7 (3.6)	6.9 (2.1)
Tacoma/Commencement Bay	8.1 (2.5)	11.8 (3.6)	6.9 (2.1)
Bangor/Hood Canal	7.3 (2.2)	11.1 (3.4)	6.6 (2.0)
Whidbey Island/Crescent Harbor	8.0 (2.4)	11.6 (3.5)	6.8 (2.1)

3.4 CURRENTS

Currents in the Puget Sound and adjacent waters are complex. The velocities of most currents in Puget Sound and adjacent waters average from one-half to two kt, with three kt currents common in some areas. The strongest currents occur with extreme tidal ranges. Some of the more restricted channels routinely have currents in the three to five kt range. Deception Pass, at the north end of Whidbey Island (Figure 1), commonly experiences diurnal ebb and flood currents of seven to eight kt. Some areas, such as Elliott Bay off Seattle, Commencement Bay off Tacoma, and Port Orchard near Keyport have weak and variable currents except when a wind driven current is present. Specific current information for each port is listed in Section 4.

3.5 WATER TEMPERATURES

Water temperatures in Puget Sound and the Strait of Juan de Fuca vary by approximately eight to nine degrees Fahrenheit from summer to winter. The water temperature in the Strait is generally 2°F (1.1°C) cooler than the waters of central Puget Sound. According to U.S. Department of Commerce (1986), winter temperatures vary from 46°F (7.8°C) at Seattle and 44°F (6.7°C) at Port Townsend to 45°F (7.2°C) at Neah Bay. Summer temperatures vary from 56°F (13.3°C) at Seattle and 54°F (12.2°C) at Port Townsend to 53°F (11.7°C) at Neah Bay.

Because of the relatively cold water temperatures, survivability of personnel who are immersed in the water by falling overboard or other means, is severely jeopardized. Hypothermia resulting from immersion, either intentional or unintentional, is a life-threatening hazard that must be taken seriously. Non-swimming, average person has a life expectancy of approximately two hours in calm water with a temperature of 44°F (7°C), and four hours in calm water with a temperature of 56°F (13°C). The times could be reduced to one and two hours respectively for “fast coolers,” i.e. persons of low body weight, children, light clothing, or those who are exercising such as persons without PFDs who must swim to remain afloat.

4.0 PUGET SOUND PORTS AND HARBORS OF INTEREST TO THE U.S. NAVY

4.1 NAVAL STATION, EVERETT

4.1.1 Location.

Naval Station (NAVSTA), Everett is located at approximately 47°59'00"N 122°13'50"W on the northeast side of Possession Sound (Figure 4). NAVSTA Everett was designed as a homeport for a U.S. Navy Battle Group. It accommodates the USS Abraham Lincoln (CVN-72) a Nimitz Class aircraft carrier as well as several smaller surface combatants.

Figure 4. Location of Naval Station Everett on Possession Sound.

4.1.2 Port Facilities.

The primary ship berthing facility at NAVSTA Everett is one long pier, designated as Pier Alpha (Figure 5). Mooring is available on both sides of the pier. A second pier is designated as Pier Bravo. Pier Alpha is 1,620 ft (494 m) long, with a width of 120 ft. Pier Bravo's western side is of rip-rap construction and acts as a breakwater. Its eastern, moorage side is slightly shorter than Pier Alpha, with similar width.

Figure 5. Pier configuration at Naval Station, Everett.

Pier Alpha's alongside depths range from 29 ft (8.8 m) at the northeast end to 65 ft (19.8 m) at the southwest end on the east side of the pier. A 1996 survey revealed that the depths between piers Alpha and Bravo, including alongside depths at Pier Bravo, range from 43 to 45 ft. Local authorities state that deck heights for both piers range from eight ft above extreme high water level to 27 ft above extreme low water level, or 22.5 ft above mean lower low water.

The anchorage for the port is located approximately two nmi west of Pier Bravo at 47°58'54"N 122°14'40"W. No U.S. Navy ship had used the anchorage as of an April 1995 port visit, but holding is reported to be good on a bottom of sand and mud. Buoy "Alfa Oscar" (AO) marks a submerged obstruction near the center of the anchorage.

NAVSTA Everett has no tugboat complement. Tugs used at the port are primarily commercial because U.S. Navy tugs must travel from the Submarine Base at Bangor, a distance of approximately 34 nmi. Requests for tugs should be directed to Senior Officer Present Afloat (SOPA) (Admin) Puget Sound at least 72 hours in advance of anticipated time of movement. Commercial tugs monitor Channel 7A (156.9 MHz), Channel 10 (156.5 MHz), Channel 77 (156.875 MHz), and Channel 13 (156.650 MHz) Bridge-to-Bridge (DMAHTC, 1993).

Regulations issued by the SOPA specify that Harbor Pilots are required only if the ship will be using two or more tugs. Aircraft carriers require four tugs, AOEs two tugs, and AEs two tugs. FFGs, which have a single screw and a bow thruster, normally have one tug standing off in case it is needed. The NAVSTA Everett Port Services Officer arranges pilot and tug services for Puget Sound ports and activities other than the Puget Sound Naval Shipyard, Bremerton and Naval Submarine Base, Bangor. Ships bound for NAVSTA Everett will board Pilots near Buoy "AO" (Figure 4) in the anchorage west of Pier Bravo.

4.1.3 Adjacent Topography.

The topography adjacent to NAVSTA Everett is depicted in Figure 6. A rise exceeding 200 ft (61 m) extends southward approximately one nmi south of Pier Alpha. Another, somewhat higher, rise extends northward approximately four nmi north of the pier. The area immediately adjacent to and northeast of the port is mostly low-lying wetlands at the mouth of the Snohomish River. The city of Everett is somewhat hilly, but the maximum elevations are less than 200 ft (61 m). The foothills of the Cascade Mountains begin east of Everett on the east side of the Snohomish River waterway.

Figure 6. Topography adjacent to NAVSTA Everett.

4.1.4 Normal and Extreme Conditions at the Port.

4.1.4.1 Wind.

The prevailing wind during summer at the Port of Everett is northwesterly. A typical day starts with relatively calm conditions through mid to late morning. By noon, a north to northwesterly sea breeze regime takes effect, with wind speeds gradually increasing to 10 to 15 kt by late afternoon. The sea breeze normally lasts until late evening, when the winds again abate to near calm conditions.

There are frequent variations to this pattern that are dependent on the pressure distribution over western Washington. Weak low pressure systems migrate through the area during the summer, preceded by southerly winds and followed by north to northwesterly winds at Everett. If high pressure predominates over western Washington during summer, relatively calm winds and warm temperatures usually result. The weakening of the high pressure system is usually followed by a strong push of cool, marine air eastward through the Strait of Juan de Fuca. While strong winds (³20 kt) are not common during summer at any location in Puget Sound, the initial push of marine air through the Strait often brings winds of 20 kt or more to the west side of Whidbey Island and through Admiralty Inlet. Northerly winds funneling southward through Saratoga Passage between Whidbey and Camano Islands (Figure 2) may reach NAVSTA Everett.

Southerly winds predominate in winter. As discussed further in Appendix A, transient extratropical low pressure systems and their associated frontal systems frequently move through the Puget Sound region in late autumn, winter, and early spring. The southerly flow preceding the frontal systems and advancing low pressure centers can reach gale velocities (34-47 kt), but NAVSTA Everett’s location just north of terrain with elevations exceeding 200 ft (Figure 6) protects it from the strongest winds. If the low pressure center moves east of Puget Sound, the passage is usually followed by a period of strong, post-frontal, northwesterly winds. As is the case during the summer, northerly winds funneling southward through Saratoga Passage between Whidbey and Camano Islands may reach NAVSTA Everett. Because of pier location and orientation, northerly winds would have little, if any, effect on harbor operations.

4.1.4.2 Waves.

Pier facilities at NAVSTA Everett are well protected from significant wave motion. Northwesterly swell may reach six to eight ft outside the inner portion of the port during periods of strong synoptic scale west to northwesterly flow over Puget Sound, but does not impact NAVSTA Everett piers. The new pier (Pier Bravo) discussed in Section 4.1.2 will be of breakwater type construction, with rip-rap on the west (outer) side. The berthing space is on the east (inner) side adjacent to Pier Alpha. The construction will further reduce the effects of waves on vessels moored at the port.

Lilly’s 1983 publication Marine Weather of Western Washington contains a compilation of potential wave generation values for specific wind directions and speeds in Puget Sound. Wave heights for the water area adjacent to Naval Station, Everett have been excerpted from that publication and are listed in Table 2. The specific point for which calculations were made is located three nmi northeast of Elliot Point (Figure 4).

Table 2. Wave heights (in feet) in Possession Sound for listed wind directions, speeds and duration periods. The specific point for which calculations were made is located three nmi northeast of Elliot Point. Adapted from Lilly (1983).

	South-Southwest Wind			North-Northwest Wind
	Duration in hours			Duration in hours
Wind Speed (kt)	1	2	3	1	2	3
10	0.3	0.8	1.2	0.3	0.8	0.9
20	1.8	2.7	2.8	1.8	2.3	2.3
30	3.2	4.3	4.3	3.2	4.6	4.6
40	4.8	6.2	6.2	4.8	5.0	5.0
50	6.7	8.0	8.0	6.6	6.6	6.6
60	8.6	9.8	9.8	8.1	8.1	8.1
70	11.0	12.0	12.0	9.7	9.7	9.7

4.1.4.3 Visibility.

Comprehensive visibility statistics for the Everett area are not available. However, Overland and Walter (1983) contains a listing of monthly percentage frequencies of occurrence of fog for various locations around Puget Sound, including Everett. The data are based on the ten-year period 1949-1958. Table 3 lists the percentage frequency of occurrence of fog (visibility less than seven nmi) at Everett.

Table 3. Percentage frequency of occurrence of fog at Everett, WA. Adapted from Overland and Walter (1983).

JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
22	21	12	8	7	13	12	16	21	30	28	24	18

4.1.4.4 Precipitation.

Precipitation records are not available for Everett, but as can be seen in Figure A-9 in Appendix A, NAVSTA Everett receives an average of approximately 34 inches total annual rainfall. Most of the precipitation falls during the four-month period of November through February. The combined rainfall for the months of July and August averages less than five percent of the annual total for the Puget Sound region (Overland and Walter, 1983). See Figure A-10 in Appendix A for a composite monthly precipitation distribution graph for south, central and north Puget Sound.

Everett is located in an area that is often affected by the "Puget Sound Convergence Zone." Weather in the convergence zone area is characterized by frequent showers. The convergence zone is caused by the splitting of low level, westerly airflow around the Olympic Mountains west of Puget Sound and subsequent convergence as the airflow merges east of the Olympics. It is most active following the passage of a cold front when the synoptic weather pattern brings generally westerly flow to the Puget Sound region, but can occur anytime westerly flow is present, including the summer season. Summer time convergence zone activity is usually limited to late afternoon and/or early evening hours. A strong surge of westerly flow can cause heavy showers and/or thundershowers. In the November through March period, snow and/or soft hail showers are common in the convergence zone. The convergence zone phenomenon is discussed further in Section 1.6 of Appendix A.

4.1.4.5 Currents.

Currents within the water area of the Naval Station are weak and ill defined. Similarly, currents away from the Snohomish River entrance just west of the Naval Station are generally weak. Currents in the river vary with the tide and weather. South-setting currents at the river's mouth may reach 4 to 8 kt during ebb tides and during periods of precipitation and/or heavy snow melt in the Snohomish River watershed.

4.1.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by Automated Digital Network (AUTODIN) to Address Indicator Group (AIG) 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.1.5.1 Strong Southerly Winds.

The only identified hazard at NAVSTA Everett is strong wind. Although not a direct hazard to ships securely moored to Piers Alpha or Bravo, strong winds could pose difficult ship handling situations for ships arriving or departing the port and could impact otherwise routine pierside operations. Winds of 20 kt or greater (small craft warning velocities) can create hazardous boating conditions for small boats going to/from the anchorage. The guidelines used by operational forecasters at the National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.1.5.2 Convergence Zone.

Although not a truly hazardous weather condition to fleet units, the formation of a convergence zone can produce precipitation in sufficient amounts and intensity to adversely affect operations in exposed areas aboard ship and on the Naval Station. A convergence zone can be expected anytime a westerly flow prevails over the Puget Sound region. Circumstances particularly favorable for the formation of a convergence zone exist during winter and spring when many transient low pressure systems migrate through the area. Lilly (1983) outlines specific criteria to look for when determining whether or not a convergence zone will form. They include:

a. The pressure gradient between Seattle-Tacoma (SEATAC) Airport and Bellingham must be less than 1.5 mb, and

b. The pressure at Quillayute, WA must initially be higher than at SEATAC Airport or Bellingham, WA.

Winds in the Strait of Juan de Fuca will be westerly, and south to southwesterly winds will prevail over Puget Sound south of the formation area near Everett.

4.1.6 Protective/Mitigating Measures.

4.1.6.1 Vessels Moored to Piers Alpha and Bravo.

Ships moored at NAVSTA Everett should ensure that mooring lines are secure and tended during periods of strong winds. All loose gear and debris should be stowed in a secure location.

During late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind situation during cool or cold temperature conditions.

4.1.6.2 Vessels in the Anchorage.

Ships in the anchorage should experience no significant effects from most southerly wind events, but a strong wind could cause problems if precautions are not taken. If possible, ships should move to berths alongside Piers Alpha or Bravo. If pierside berthing is not available, using a second anchor would mitigate the effects of the wind and reduce the possibility of anchor dragging. In any strong wind event, continuous position monitoring by the use of radar and sight lines is recommended to immediately detect any indication of anchor dragging.

Strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. See Table A-2 in Appendix A for equivalent wind chill calculations.

4.1.6.3 Arriving/Departing Vessels.

Southerly winds do not pose a significant problem to ships arriving at or departing from NAVSTA Everett. The alignment of Piers Alpha and Bravo mitigate the effects of the southerly winds during docking and undocking evolutions, but strong winds could pose ship handling problems in some situations. Ships arriving at NAVSTA from the Strait of Juan de Fuca will likely encounter the strongest winds in Admiralty Inlet, along the west side of Whidbey Island.

Commanding officers should be aware of the potential for strong currents in the outflow of the Snohomish River just west of Pier Bravo, and allow for sufficient offset to counter the effects of the current.

4.1.6.4 Small Craft.

Small craft operating to/from NAVSTA Everett and ships in the anchorage must be aware of the significant impact that southerly winds will have on their operation. The runs to/from the anchorage and the piers will be perpendicular to southerly/northerly winds and waves, the most common directions at NAVSTA Everett. If winds are of small craft velocity (20-33 kt) or greater, runs should be suspended until winds and waves abate. Table 2 contains wave height calculations for a combination of wind speeds versus duration times, and should be referenced in any potentially strong wind situation.

Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind event during cool or cold temperature conditions.

Table 4 - Summary of Hazardous Environmental Conditions for Naval Station, Everett.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/SITUATION AFFECTED

EFFECT - PRECAUTIONARY/EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 The kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Waves to 8 ft or higher are possible in the anchorage and Possession Sound, but do not reach the inner warnings waters of NAVSTA Everett.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of approaching low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* Strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Duration of strong wind is dependent on speed of movement of low pressure system and/or frontal system causing the wind, and commonly last from last from 6 to 12 hours. A slow moving system will result in a longer duration.

* Low pressure systems may occur as a “family” of two or more storms, which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to Piers Alpha and Bravo.

(2) Vessels in the anchorage.

(3) Arriving/departing vessels.

(4) Small boat operations.

(5) All locations/situations.

1.a. Properly moored vessels should experience little difficulty.

* The location of NAVSTA on the east side of Possession Sound and the orientation of the piers minimize the impact of wind and waves. The short fetch area south and southwest of the piers prevents large waves from generating. The larger waves generated in to Puget Sound do not reach the piers.

2.a. Strong southerly winds are the most hazardous condition in the anchorage.

* If possible, ships should move to berths alongside Piers Alpha or Bravo.

* If pierside berthing is not available, a second anchor should be considered to mitigate the effects of the wind and reduce the possibility of anchor dragging. Continuous position monitoring by the use of radar and sight lines is recommended.

3.a. Southerly winds do not pose a significant problem ships arriving at or departing from NAVSTA Everett.

* The alignment of Piers Alpha and Bravo lessen the effects of the southerly winds during docking and undocking evolutions, but a strong wind could pose ship handling problems.

* Ships arriving at NAVSTA from the Strait of Juan de Fuca will likely encounter the strongest winds in Admiralty Inlet.

4.a. Southerly winds bring the most hazardous conditions for small craft operating west of Piers Alpha and Bravo.

* Runs to/from the anchorage will be perpendicular to southerly winds. If winds are of small craft warning velocity (³20 kt), operations outside the immediate area of the piers should be suspended until the winds abate.

5.a. The equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

* Equivalent wind chill temperatures can lower to the point where they are hazardous to exposed flesh. For example, a 30°F (-1°C) temperature, when combined with a wind speed of 20 to 23 kt, results in a wind chill temperature of 0°F (-18°C). Appropriate precautions should be taken for all personnel working in exposed locations or on weather decks. See Table A-2 in Appendix A.

4.2 NAVAL SUBMARINE BASE, BANGOR

4.2.1 Location.

The U.S. Naval Submarine Base (SUBASE), Bangor is located on the east shore of Hood Canal, with an approximate central location of 47°44'45"N 122°43'40"W (Figure 7). The pier facilities of the base are located along two nmi of waterfront.

Figure 7. Location of SUBASE Bangor on Hood Canal.

4.2.2 Port Facilities.

The primary berthing facilities at SUBASE Bangor consist of four separate pier complexes: "KB" Docks, Delta Pier, Marginal Pier, and Explosive's Handling Wharf (Figure 8, Figure 9, Figure 10, and Figure 11). Trident submarines berth at Marginal Pier South and at Delta Pier North and South. They also use the Explosives Handling Wharf and the drydock on Delta Pier. According to harbor authorities, submarines are rarely nested, and when they do, are nested only for a day or two. Pier decks have a nominal height of 20 ft above mean lower low water. Alongside water depths vary from 45 ft at Marginal Wharves North and South, to 60 to 115 ft at the Delta Piers.

Figure 8. Relative positions of wharf facilities at SUBASE Bangor.

Figure 9. Configuration of KB Docks at SUBASE Bangor.

Figure 10. Configuration of Delta Pier at SUBASE Bangor.

Figure 11. Configuration of Marginal Wharf at SUBASE Bangor.

No anchorages exist at SUBASE Bangor. Mooring buoys for barges are available near the KB docks.

SUBASE Bangor has a complement of three 2,000 hp YTB tugboats and a twin-screw 1,600 hp commercial tug. Local authorities state that pilots are used for all submarine arrivals at Bangor. Pilots can be picked up at any point in the area from Foul Weather bluff at the entrance to Hood Canal southward to off Bangor, as requested. If a submarine commanding officer has passed through the Hood Canal Bridge once, a pilot is optional on departures. If tug assistance is required, pilotage is mandatory (DMAHTC, 1993).

4.2.3 Adjacent Topography.

Topography on both sides of Hood Canal commonly exceeds 400 ft (122 m) (Figure 3 and Figure 12). The Olympic Mountain range, with elevations over 7,000 ft (2,134 m), lies a few miles west of Hood Canal. Because of funneling effects of the significant elevations on both sides of the waterway, Hood Canal can experience strong southwesterly winds during periods of synoptic scale southerly flow.

Figure 12. Topography adjacent to SUBASE Bangor.

4.2.4 Normal and Extreme Conditions at the Port.

4.2.4.1 Wind.

Southwesterly winds directly impact Bangor's dock facilities due to the orientation of Hood Canal. Winds are amplified as they are funneled northeastward through the canal by the orientation of the canal with respect to the adjacent topography. Operations at the Explosives Handling Wharf, Delta Drydock, and the Magnetic Silencing Facility will cease if wind velocities reach 25 kt. Wind alone is not a problem for moored submarines, but it does cause waves to wash over their hulls.

The KB Docks are used by small craft from the Naval Undersea Weapons Engineering Station (NUWES) at Keyport. Bangor harbor pilots state that lines are doubled and dead-man lines and buoys are used to prevent excessive motion of moored vessels during periods of strong southwesterly winds. Most vessels are moored on the inboard side of the piers, but YTT's (torpedo recovery boats - 135-140 ft long/1,600 tons) moor to the outside of the piers and are exposed to whatever conditions exist in Hood Canal.

Anytime winds approach 50 kt, the Hood Canal Bridge is closed to auto traffic and kept in an open position to reduce wind stress on the bridge structure. The floating bridge was partially destroyed by winds/waves on February 13, 1979 during an extremely strong wind storm. The event is discussed further in Section 6.1.4 of Appendix A.

4.2.4.2 Waves.

The southwest berth of Delta Pier and the KB docks experience four to six ft swell during periods of strong (up to 60 kt) winds. As long as access hatches on submarine hulls are closed, the waves do not pose a direct problem to submarines. However, if tugs are alongside a submarine, wave motion may cause the tugs to pitch up and down with potential damage to the submarine hull. To preclude such damage, normal tug operations are suspended in strong wind situations.

Table 5. Wave heights (in feet) in Hood Canal for listed wind directions, speeds and duration periods. Adapted from Lilly (1983).

	Southwest Wind		Northwest Wind
	Duration in hours		Duration in hours
Wind Speed (kt)	1	2	1	2
10	0.3	0.6	0.3	0.6
20	1.8	1.9	1.8	1.9
30	3.0	3.0	3.0	3.0
40	4.2	4.2	4.2	4.2
50	5.3	5.3	5.3	5.3
60	6.8	6.8	6.8	6.8
70	7.9	7.9	7.9	7.9

4.2.4.3 Visibility.

Hood Canal does not have a regular weather observation site, so records of visibility observations for Bangor are not available. Like most locations on Puget Sound, SUBASE Bangor’s incidence of fog would be at a minimum in late spring and early summer and greatest during the months of October and November.

4.2.4.4 Precipitation.

Because there is no official weather recording site at Bangor, precipitation records are not available. As can be seen on Figure A-9 in Appendix A, SUBBASE Bangor receives an average of approximately 40 inches total annual rainfall. Most of the precipitation falls during the four-month period of November through February. The combined rainfall for the months of July and August averages less than five percent of the annual total for the Puget Sound region (Overland and Walter, 1983). See Figure A-10 in Appendix A for a composite monthly precipitation distribution graph for south, central and north Puget Sound.

4.2.4.5 Currents.

Currents in Hood Canal, a semi-enclosed basin, are largely tide driven. Northeast setting ebb currents in the range of 1.0 to 1.2 kt are common adjacent to the SUBASE. Because of the steep terrain on both sides of Hood Canal, heavy rain causes heavy runoff. The increased runoff adds to tidal flow during the ebb, increasing the current speed to two kt. Local authorities state that submarines leaving the south berth at Delta Pier during a strong ebb flow have difficulty moving into the current and away from the pier. Southwest setting flood currents are normally in the 0.6 to one kt range.

4.2.5 Indicators of Hazardous Weather Conditions.

Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOD Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.2.5.1 Strong Southwesterly Winds.

The only identified hazard at SUBASE Bangor is a strong southwesterly wind funneling through Hood Canal. Because of their low hull profile, wind does not pose a direct hazard to submarines. It can, however, impact the ability of tugs to work alongside submarines. It would also affect the operations of small craft and YTT’s from NUWES Keyport utilizing the KB Dock complex. The guidelines used by operational forecasters at NWSFO, Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.2.6 Protective/Mitigating Measures.

4.2.6.1 Vessels Moored to Berths.

Submarines and other vessels moored at SUBASE Bangor should ensure that mooring lines are secure and tended during periods of strong southwesterly winds. All loose gear and debris should be stowed in a secure location. Waves raised by the wind may cause hull washover, so hull access hatches should be closed to preclude water entry. At KB docks, personnel should ensure that lines are doubled and dead-man lines and buoys are used to prevent excessive motion of moored small craft, including YTT’s during periods of strong southwesterly winds.

4.2.6.2 Arriving/Departing Vessels.

Because of the low profile of the submarine hulls, strong southwesterly winds should pose no significant problems to arriving and departing submarines, but tug boats assisting in the docking or undocking evolutions are another matter. The waves raised by the wind can cause tug boats to pitch up and down and endanger the submarine’s hull. If waves that would cause excessive motion by the tug boats exist or are forecast, it is recommended that docking and undocking operations be suspended until wave conditions abate.

Wind chill must be considered for personnel working in exposed locations on weather decks during strong wind situations. Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind event during cool or cold temperature conditions.

Table 6 - Summary of Hazardous Environmental Conditions for Submarine Base, Bangor.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 The kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Waves in Hood Canal adjacent to the SUBASE may reach 6 to 8 ft in less than one hour if wind speeds approach 60 kt.

Advance Warning

* Twice daily forecasts for inland waters, including Hood Canal, are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound, Hood Canal and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of approaching low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* Strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms, which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to Delta, Marginal wazzu and Explosives Handling Piers.

(2) Small craft moored to KB Docks.

(3) Arriving/departing vessels.

(4) All locations/situations.

1.a. Properly moored vessels should experience little difficulty. Low profile of submarine hulls mitigates excessive motion caused by wave motion.

* Submarines moored to Delta Pier South will experience the brunt of the wind and/or seas moving northeast through Hood Canal. Waves may cause washover of hulls; so all exterior hatches should be closed.

2.a. Vessels are exposed to waves moving northeast through Hood Canal.

* Responsible personnel should ensure that small craft and YTT’s are securely moored.

* Lines should be doubled and dead-man lines and buoys used to prevent excessive motion.

3.a. Inbound/outbound submarines should experience little difficulty.

* Tugboats operating alongside submarines pose a hazard to submarine hulls due to the pitching motion of the tug bows induced by wave motion. Docking and undocking operations should be suspended until hazardous wave conditions abate.

4.a. The equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

4.3 PUGET SOUND NAVAL SHIPYARD, BREMERTON

4.3.1 Location.

Puget Sound Naval Shipyard (PSNS), Bremerton is located on the north side of Sinclair Inlet at approximately 47°33'00"N 122°38'30"W (Figure 13). Sinclair Inlet is reached from Puget Sound by passing through Rich Passage and the waters of Port Orchard.

Figure 13. Location of Puget Sound Naval Shipyard, Bremerton on Sinclair Inlet.

4.3.2 Port Facilities.

PSNS Bremerton is a large facility. It has nine piers with a total of 12,310 ft (3,752 m) of deep water mooring space. Individual berths range from 700 ft (213 m) to 1,400 ft (417 m) with alongside depths ranging from 30 to 44 ft (9.1 to 13.4 m) (Figure 14). Pier heights are 17 ft above zero tide level. All piers are oriented north-south. Due to the prevailing southwesterly winds, the preferred berths are on the west side of the piers. The shipyard has six dry docks, one of which is 1,152 ft (351 m) long, the largest in the U.S. Navy.

Figure 14. Pier configuration at Puget Sound Naval Shipyard, Bremerton.

Four mooring buoys are available in Sinclair Inlet:

Buoy L-1 is used for barges only.

Buoy A-11 is a class D mooring and is good for 85 kt winds with an AS (Submarine Tender) moored to it.

Buoy A-12 is a class B mooring and is good for 85 kt winds with a CVA class aircraft carrier moored to it.

Buoy A-13 is a class C mooring and is good for 85 kt winds with an AD (Destroyer Tender), AO (Fleet Oiler) or similarly sized vessel moored to it.

As of April 1996, the shipyard was Home Port to seven U.S. Navy ships. The home ported ships include one nuclear-powered aircraft carriers (CVN), three fast combat support ships (AOE) and two nuclear-powered cruisers (CGN).

Because of numerous underwater cables, there are no anchorages near the shipyard. The nearest designated anchorage is located northwest of Blake Island in Puget Sound. Its position is indicated by a circled letter “A,” approximately one nmi southeast of the east end of Rich Passage on Figure 13. Depths in the anchorage range from 90 to 390 ft. Holding is rated as good on a mud bottom. Harbor authorities at Bremerton state that the anchorage is exposed to north and south winds, but can be used by a CVN during storm force (³47 kt) winds. PSNS Bremerton does not have a designated Fleet Landing for ships using the anchorage.

PSNS Bremerton has a complement of two 2,000 hp (YTB) tugs. One tug is available 24 hours a day. The second is available during normal working hours only. Commercial tugs are available from the Port of Seattle.

4.3.3 Adjacent Topography.

The topography adjacent to Bremerton is depicted in Figure 15. Elevations exceeding 200 ft (61 m) exist north and south of the shipyard. Elevations exceed 1,000 ft (305 m) approximately three nmi west of the facility. As the figure shows, the topography provides channeling for southwesterly winds to reach the pier area of the shipyard.

Figure 15. Topography adjacent to Puget Sound Naval Shipyard, Bremerton.

4.3.4 Normal and Extreme Conditions at the Port.

4.3.4.1 Wind.

Winds at the shipyard are measured by an anemometer located in a tower near Dry Dock #6. The local harbor authorities state that the anemometer is only minimally affected by adjacent buildings. The anemometer’s measurements are considered to be representative of winds experienced at the port.

The shipyard experiences strong southwesterly winds due to the funneling effects of the Olympic Mountain Range and nearby topography. The shipyard experiences no problem with winds from other directions.

4.3.4.2 Waves.

Wave motion is limited at the shipyard due to the lack of fetch to the southwest. According to local harbor authorities, the anchorage northwest of Blake Island is more vulnerable to wave motion, but ships in the anchorage are not likely to experience wave-related problems. Maximum wave heights are: pierside berths, 1 to 1.5 ft; buoys, 1.5 to 2 ft; and 2 to 2.5 ft in the anchorage.

4.3.4.3 Visibility.

According to local authorities, fog is a minor problem during early morning hours in late spring and early autumn. Specific climatic data for Bremerton are not available, but Bremerton’s location in central Puget Sound west of Seattle would indicate that it’s incidence of fog would be approximately the same as Seattle’s. There will be a difference due to Bremerton being located on Sinclair Inlet on the west side of Puget Sound, but the amount of the difference is unknown. Table 7 lists the mean number of days with fog (visibility less than seven nmi) at SEATAC Airport just south of Seattle and Olympia in the extreme south end of the Sound. The elevation of SEATAC is 450 ft above mean sea level (msl), so SEATAC’s visibility would occasionally be restricted by low clouds that would not hamper visibility at sea level in Puget Sound. Olympia’s elevation is 192 ft above msl.

Table 7. Mean number of days with fog at Olympia, WA and SEATAC Airport. Adapted from Federal Climate Complex, Asheville (1995).

	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
OLYMPIA	25	21	20	15	11	10	10	15	21	26	25	26	225
SEATAC	18	14	12	9	8	8	8	12	16	19	18	19	161

4.3.4.4 Precipitation.

As shown on Figure A-9 in Appendix A, Bremerton receives a mean annual precipitation total of approximately 50 inches. A month-by-month breakdown is not available. However, most of the precipitation in the Puget Sound region falls during the four-month period of November through February. The combined rainfall for the months of July and August is less than five percent of the annual total (Overland and Walter, 1983). See Figure A-10 in Appendix A for a composite monthly precipitation distribution graph for south, central and north Puget Sound.

4.3.4.5 Currents.

Currents in Sinclair Inlet adjacent to the shipyard are weak and ill defined. However, currents of up to five kt are common in the west end of Rich Passage. The directions of the currents are tide dependent, setting west on a flood tide and east on the ebb. Velocities are similar for both ebb and flood tides.

4.3.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.3.5.1 Strong Southwesterly Winds.

The only identified hazard at PSNS Bremerton is strong southwesterly winds. The shipyard experiences strong southwesterly winds due to the funneling effects of the Olympic Mountain Range and nearby topography. A strong storm system with 70 kt winds forced a CVN on to her mooring in January 1993. The same storm caused two inactive submarines to part their moorings. The guidelines used by operational forecasters at NWSFO, Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.3.6 Protective/Mitigating Measures.

4.3.6.1 Ships Moored at PSNS Bremerton Piers and Moorings.

Ships moored at PSNS Bremerton should ensure that mooring lines are secure and tended during periods of strong winds. All loose gear and debris should be stowed in a secure location. Strong southwesterly winds tend to force ships mooring to the west side of the piers on to their berths. Similarly, the winds also tend to force ships mooring to the east side of the piers off of their berths. Ships moored to the lee (east) side of the piers and moorings should ensure that adequate lines are used to counter the offsetting effects of the wind. Lines should be tended.

4.3.6.2 Ships in the Anchorage Northwest of Blake Island.

Harbor authorities state that the anchorage is exposed to north and south winds, but can be used by a CVN during storm force (³47 kt) winds. Consequently, ships in the anchorage should experience little difficulty in strong wind situations. It is recommended that radar and sight fixes be maintained to detect any tendency to drag anchor. Strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Appropriate precautions should be taken.

4.3.6.3 Arriving/Departing Vessels.

Because of the north-south orientation of PSNS Bremerton’s piers, strong southwesterly winds tend to force ships mooring to the west side of the piers on to their berths. Similarly, the winds also tend to force ships mooring to the east side of the piers off of their berths. Harbor pilots are well aware of the problem, and take adequate precautions when ships are mooring or departing their berths. The strongest southerly winds encountered by inbound and outbound units will likely be experienced in Admiralty Inlet west of Whidbey Island (Figure 2).

Commanding officers of inbound or outbound units should be aware of the strong currents (up to five kt) that may exist near the west end of Rich Passage. Strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Appropriate precautions should be taken. See Table A-2 in Appendix A for equivalent wind chill calculations.

4.1.6.4 Small Craft.

Small craft operating to/from vessels in the anchorage northwest of Blake Island and PSNS Bremerton have a run of approximately seven nmi. Except for a segment in Rich Passage, the boat run would be in waters exposed to south and southwesterly winds. It is recommended that small craft operations to and from the anchorage and PSNS Bremerton be suspended anytime small craft velocity (20-33 kt) or greater winds are forecast.

Strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel responsible for the operation of small craft should be aware of the equivalent wind chill factor and ensure that appropriate precautions are taken when indicated. See Table A-2 in Appendix A for equivalent wind chill calculations.

Table 8 - Summary of Hazardous Environmental Conditions for Puget Sound Naval Shipyard, Bremerton.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Waves on Sinclair Inlet are minimal due to limited fetch area to southwest.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind warnings are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Duration of strong wind is dependent on speed of movement of low pressure system and/or frontal system causing the wind, and commonly last from 6 to 12 hours. A slow moving system will result wazzu in a longer duration.

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to piers and moorings.

(2) Vessels in the anchorage northwest of Blake Island.

(3) Arriving/departing vessels.

(4) Small boat operations.

(5) All locations/situations.

1.a. Properly moored vessels should experience little difficulty.

* Vessels moored to the west side of the piers and moorings will be forced against their berths.

* Vessels moored on the east side of the piers and moorings will be forced off their berths.

* Lines should be doubled and extra lines utilized to counter the off-setting force of the wind.

2.a. Anchored vessels will be exposed to the full force of the wind.

* Holding ground is good. Local authorities state that a CVN can use the anchorage in winds of storm force (48 kt or greater).

* Position of the anchored vessel should be constantly monitored to detect the first indication of anchor dragging.

* Steaming to the anchor may be necessary.

3.a. Docking and undocking evolutions could be difficult due to the on- or off-setting forces of the wind.

* Only two tugs are available at PSNS Bremerton.

* There is limited maneuvering room in Rich Passage. Arrivals and departures should be delayed until strong winds abate.

4.a. Most of the run to/from the anchorage to PSNS Bremerton is exposed to south and southwesterly winds.

* If winds are of small craft warning velocity (³20 kt), operations outside the immediate area of the piers should be suspended until the winds abate.

5.a. The equivalent wind chill temperature must be considered during periods of cold weather.

4.4 NAVAL UNDERSEA WEAPONS ENGINEERING STATION, KEYPORT.

4.4.1 Location.

Naval Undersea Weapons Engineering Station (NUWES), Keyport is a small facility located at approximately 47°42'12"N 122°37'00"W (Figure 16). Keyport is positioned on a small promontory on the south side of a narrow passage that connects Liberty Bay with the northwest end of the waters of Port Orchard.

Figure 16. Location of NUWES Keyport between Liberty Bay and the waters of Port Orchard.

4.4.2 Port Facilities.

NUWES Keyport has two piers, designated as Pier 1 and Pier 2 (Figure 17). Pier 1 has a moorage length of 495 ft, a width of 76 ft, and an alongside depth of 21 ft. Pier 1 can accommodate two YTT’s. Pier 2 has a moorage length of 950 ft, a width of 48 ft, and an alongside depth of 19 ft. Pier 2 can accommodate ten small craft. Deck height of each pier is 17.6 ft above mean lower low water (MLLW).

Figure 17. Piers at NUWES Keyport.

4.4.3 Adjacent Topography.

The topography adjacent to NUWES Keyport is depicted in Figure 18. Elevations exceeding 200 ft (61 m) exist north and south of the pier facilities. The open waters of Port Orchard between the land mass south of NUWES Keyport and Bainbridge Island provide a channel for southerly winds to reach the piers of the facility, especially Pier 1.

Figure 18. Topography adjacent to NUWES Keyport.

4.4.4 Normal and Extreme Conditions at the Port.

4.4.4.1 Wind.

South to southwesterly is the prevailing wintertime wind direction, and is commonly observed from late autumn through early spring. Unfortunately, it is the worst wind direction for the facility. Because small craft are the primary users of the facility, they are adversely impacted whenever strong winds are present. Vessels will not be moved if small craft warnings are issued.

4.4.4.2 Waves.

Local authorities state that wave motion is negligible at Keyport.

4.4.4.3 Visibility.

There is no regular weather observation station near Keyport, so specific climatic data are not available. Keyport is located approximately six nmi north of Bremerton, so the visibility statistics should be approximately the same. Refer to Section 4.3.4.3 for a discussion of Bremerton’s visibility.

4.4.4.4 Precipitation.

Keyport is located in an area that receives approximately 40 inches of precipitation in an average year (Figure A-9 in Appendix A). There is no regular observation site near Keyport, so monthly accumulations are not known. However, Figure A-10 in Appendix A shows the monthly distribution of precipitation at four sites in the Puget Sound region including SEATAC Airport south of Seattle. Since Keyport’s yearly precipitation total closely approximates that of SEATAC Airport in Seattle, the monthly amounts should be similar. As shown in Figure A-10, and according to Overland and Walter (1983), most of the precipitation in the Puget Sound region falls during the four-month period of November through February. The combined rainfall for the months of July and August averages less than five percent of the annual total.

4.4.4.5 Currents.

Currents near Keyport are weak and ill defined.

4.4.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.4.5.1 Strong South to Southwesterly Winds.

As previously stated, the primary hazard at NUWES Keyport is strong south to southwesterly winds. The guidelines used by operational forecasters at NWSFO, Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.4.6 Protective/Mitigating Measures.

Since small craft moored at NUWES Keyport are not moved during winds of 20 kt or more (small craft warning velocities), moving to a more protected location is not an option. Responsible personnel should ensure that mooring lines are secure and tended at both piers during periods of strong winds. Such precautions are particularly necessary at the more exposed Pier 1. All loose gear and debris should be stowed in a secure location.

Small craft that are located away from NUWES Keyport during the onset of strong southerly winds can seek shelter in any of several more protected sites. Vessels transiting the Strait of Juan de Fuca going to/from coastal operating areas can find shelter at Neah Bay or Port Angeles (Figure 1).

Table 9 - Summary of Hazardous Environmental Conditions for Naval Undersea Weapons Engineering Station, Keyport

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Due to lack of fetch, wave motion is not a problem at Keyport.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind warnings are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of low pressure systems and/or frontal systems as they approach the Puget Sound region from Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to Piers 1 & 2.

(2) Vessels transiting to/from off-shore operating areas along Washington coast.

(3) All locations/situations.

1.a. Vessels moored to Pier 1 are more exposed to southerly winds and waves, but properly moored vessels should experience little difficulty at either location.

* Responsible personnel should ensure that mooring lines are secure and tended during periods of strong winds.

2.a. Strong winds and high waves in the Strait of Juan de Fuca may prevent safe transit.

* Southerly the winds in Puget Sound usually result in easterly winds in the Strait of Juan de Fuca. Due to funneling, small craft velocities (³20 kt) in Puget Sound may result in gale force winds (³34 kt) in the Strait.

* The harbors of Neah Bay and Port Angeles are safe havens for small vessels during periods of strong winds.

3.a. The equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

4.5 NAVAL AMMUNITION DEPOT, INDIAN ISLAND

4.5.1 Location.

Indian Island is located west of Marrowstone Island between the waters of Port Townsend and Kilisut Harbor. Indian Island is approximately 4.2 nmi long and oriented on a north-south axis between Marrowstone Island and the mainland of the Quimper Peninsula. The Naval Ammunition Depot (NAD) is located on the northwest side of Indian Island. The Ammunition Pier, the facility of interest to this evaluation, is located on the extreme northwest part of the island at approximately 48°04'30"N 122°45'00"W (Figure 19).

Figure 19. Location of the Ammunition Pier of NAD, Indian Island on Port Townsend.

4.5.2 Port Facilities.

The Ammunition Pier (Figure 20) is the primary maritime facility of NAD Indian Island. It is large enough to accommodate a Nimitz class aircraft carrier (1,040 ft long/91,487 to 96,358 tons). The pier is 1,500 ft (457 m) long, not counting tug berths on mooring floats on the south end of the pier. According to harbor pilots at Bremerton, the wooden pilings used in the construction of the pier would not support an aircraft carrier in an on-setting wind, so steel pilings 600 ft apart were installed. Because of the distance between the steel pilings, camels are now needed by moored ships to accommodate the pilings.

Figure 20. Configuration of the Ammunition Pier at NAD, Indian Island.

A second, older pier is located on the west side of the island south of the ammunition pier, but a 200 ft section was lost in a severe wind storm. It has not been rebuilt and is now condemned.

Alongside depths at the Ammunition Pier are 50 ft (15.2 m) or more. The depths increase rapidly away from the pier.

Two explosives anchorages are noted on DMAHTC Chart 18464, Port Townsend. One is a fair weather anchorage located on Port Townsend approximately 4,000 yd (3,658 m) northeast of the Ammunition Pier. The second is a foul weather anchorage located approximately 600 yd (549 m) south of the south end of the Ammunition Pier. United States Coast Pilot 7 mentions a "usual" anchorage of unspecified holding quality about 0.5 to 0.7 nmi south of the “railroad ferry terminal” at Port Townsend, on a muddy bottom in depths of 48 to 60 ft (14.6 to 18.3 m). The location would place the anchorage approximately 1.4 nmi north-northwest of the Ammunition Pier. The same document states that in southerly gales, better anchorage is afforded close inshore off the north end of Marrowstone Island or near the head of the bay on a muddy bottom in “moderate depths.”

Ships at the Ammunition Pier are serviced by tugs from SUBASE Bangor for docking and undocking evolutions.

4.5.3 Adjacent Topography.

Figure 21 depicts the topography immediately adjacent to the Ammunition Pier on Indian Island. Most of the higher elevations in the area are oriented north-south, including the rises on Quimper Peninsula, Indian Island and Marrowstone Island. It is easily seen that the water area between Indian Island and the Quimper Peninsula provides a channel for southerly winds to reach the Ammunition Pier.

Figure 21. Topography adjacent to Ammunition Pier at NAD Indian Island.

4.5.4 Normal and Extreme Conditions at the Port.

4.5.4.1 Wind.

Southerly winds prevail during wintertime, and are commonly observed from late autumn through early spring. Unfortunately, a southerly direction has the greatest adverse impact on the facility. Southerly winds reach the Ammunition Pier as south-southeasterly, and strong winds can affect docking evolutions.

Late spring, summer, and early autumn winds are generally light during the night and early morning hours, shifting to northwesterly during the afternoon. Northwesterly wind velocities are reduced by the terrain northwest of Port Townsend. Southerly winds do occur, however, with the approach and passage of an occasional frontal system through the region.

4.5.4.2 Waves.

Because of its protected location on Port Townsend, wave motion is not a problem at the Ammunition Wharf. Waves in Admiralty Inlet just outside of Port Townsend can be a problem for inbound and outbound vessels during periods of strong northwesterly winds. Lilly’s 1983 publication Marine Weather of Western Washington contains a compilation of potential wave generation values for specific wind directions and speeds in Puget Sound. Wave heights for Admiralty Inlet at a location one nmi northeast of the extreme northeast point of Marrowstone Island (Figure 19) have been excerpted from that publication and are listed in Table 10.

Table 10. Wave heights (in feet) in Admiralty Inlet at a point one nmi northeast of Marrowstone Island for northwest winds at the listed wind speeds and duration periods. Adapted from Lilly (1983).

	Northwest Wind
	Duration in hours
Wind Speed (kt)	1	2	3	4	5	6	7
10	0.3	0.8	1.2	1.3	1.4	1.5	1.7
20	1.8	2.7	3.2	3.7	4.0	4.0	4.0
30	3.2	4.6	5.7	6.5	6.5	6.5	6.5
40	4.8	7.0	8.7	9.1	9.1	9.1	9.1
50	6.7	9.8	12.0	12.0	12.0	12.0	12.0
60	8.6	13.0	15.0	15.0	15.0	15.0	15.0
70	11.0	16.0	18.0	18.0	18.0	18.0	18.0

4.5.4.3 Visibility.

Since there is no regular weather observation site located near Indian Island or Port Townsend, exact visibility statistics at the Ammunition Pier are not known. The nearest observation site is at Naval Air Station (NAS), Whidbey Island, located approximately 11 nmi north of Indian Island. The exposures are different since the Olympic Peninsula lies to the west of Indian Island, and NAS Whidbey Island is exposed to the west at the east end of the Strait of Juan de Fuca. Nevertheless, Indian Island is close to the north end of Admiralty Inlet, and should experience much of the same advection fog conditions that exist on Whidbey Island. Table 11 lists the mean number of days that fog (visibility less than seven nmi) is recorded at NAS Whidbey Island.

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Table 11. Mean number of days when fog is observed at NAS Whidbey Island. Adapted from Federal Climate Complex, Asheville (1995).

JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
10	10	8	7	6	8	10	14	15	17	11	10	126

4.5.4.4 Precipitation.

As shown on Figure A-9 in Appendix A, Indian Island receives approximately 20 inches of precipitation during an average year. Because of the absence of a nearby observation site, average monthly amounts are not known. Since its total amount approximates that of NAS Whidbey Island, monthly amounts should be similar. Figure A-10 in Appendix A shows the monthly distribution of precipitation at four sites in the Puget Sound region, including NAS Whidbey Island. As shown in Figure A-10 and according to Overland and Walter (1983), most of the precipitation in the Puget Sound region falls during the four-month period of November through February. The combined rainfall for the months of July and August averages less than five percent of the annual total.

4.5.4.5 Currents.

Currents are not a significant problem at the Ammunition Wharf. Prevailing currents within Port Townsend north of the wharf are circular, and may set clockwise or counter-clockwise, depending on wind flow and the tide. SUBASE Bangor Harbor Pilots, who service ships at the wharf, state that ebb tides cause strong currents in Admiralty Inlet. Because of the relatively narrow entrance channel, ships destined for the Ammunition Wharf must keep at least 10 kt steerage way until well west of a line between Point Wilson and Marrowstone Point. A strong north-setting current passes west of Indian Island through Port Townsend Canal (between Indian Island and the mainland of the Quimper Peninsula) during an ebb tide, but it is largely diffused by the waters of Port Townsend before it reaches the Ammunition Wharf.

4.5.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.5.5.1 Strong Southerly Winds.

The primary hazard at the Ammunition Pier is strong southerly winds. The wind moves north around both sides of Indian Island, reaching the pier as south-southeasterly. Arriving ships normally approach the pier in a wide, counterclockwise turn, and moor starboard side to the pier. During strong southerly winds, the ships are forced off of the pier, making the approach through Port Townsend difficult. Ships may, of necessity, have to moor port side to the pier because of the off-setting effect of wind and the resultant difficult approach. SUBASE Bangor harbor pilots, who provide pilot services for ships arriving at or departing the pier, state that 25 to 30 kt is the maximum wind for safe docking of most vessels at the pier, but 20 kt is the limit for aircraft carriers.

The guidelines used by operational forecasters at NWSFO, Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.5.6 Protective/Mitigating Measures.

4.5.6.1 Vessels Moored to the Ammunition Pier.

Ships moored at the Ammunition Pier should ensure that mooring lines are secure and tended during periods of strong winds. All loose gear and debris should be stowed in a secure location.

4.5.6.2 Arriving/Departing Vessels.

Arriving vessels should be aware of the offsetting effects of strong southerly winds when approaching the Ammunition Pier through the waters of Port Townsend. If the wind is sufficiently strong, a wide, counterclockwise turn that is normally used to approach the pier in order to moor starboard side to the pier, may not be possible. If the approach is not feasible, the harbor pilot will so indicate, and a more direct approach, mooring port side to the pier will be made. The strongest southerly winds experienced by an inbound or outbound vessel will likely be encountered in Admiralty Inlet, along the west side of Whidbey Island (Figure 2).

During late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Appropriate precautions should be taken. See Table A-2 in Appendix A for equivalent wind chill calculations.

4.5.6.3 Vessels in an Anchorage.

Vessels using one of the two explosives anchorages described in Section 4.5.2 should take all of the heavy weather precautions normally taken if strong winds exist or are forecast. It is recommended that radar and sight fixes be maintained to detect any tendency to drag anchor. Two anchors should be used, as necessary, to preclude anchor dragging.

Table 12 - Summary of Hazardous Environmental Conditions for Naval Ammunition Pier, NAD Indian Island.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Due to the location of the Ammunition Pier on the northwest side of Indian Island, wave motion is not a problem at the pier.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind warnings are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of approaching low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to the Ammunition Pier.

(2) Vessels in the explosives anchorage(s).

(3) Arriving/departing vessels.

(4) Small boat operations.

(5) All locations/situations.

1.a. Vessels moored to the pier are forced off their berth by the wind.

* Properly moored vessels should experience little difficulty. Lines should be doubled where necessary and tended during periods of strong wind. Extra lines should be used as the wind force dictates.

2.a. Both anchorages are exposed to winds, but wave buildup will be negligible due to lack of fetch.

* If gale force or stronger winds are forecast, a second anchor should be deployed to mitigate the effects of the wind and reduce the possibility of anchor dragging. Continuous position monitoring by the use of radar and sight lines is recommended.

3.a. Strong southerly winds affect ships approaching the Ammunition Pier. The upper limit for safe docking evolutions at the pier is 25 to 30 kt.

* Due to the offsetting force of the wind, ships intending to make a wide, counter-clockwise turn and moor starboard side to the Ammunition Pier may find it necessary to make a direct approach and moor port side to the pier.

* The narrow channel and adjacent shoal water requires ships to maintain at least a 10 kt headway when leaving Admiralty Inlet and entering Port Townsend at the north end of Marrowstone Bank. The same is true of ships leaving Port Townsend.

4.a. Runs to/from the anchorage(s) may need to be curtailed if winds of small craft warning velocity (³20 kt) exist or are forecast. Operations should not be resumed until the winds abate.

5.a. Equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

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4.6 NAS WHIDBEY ISLAND SEAPLANE BASE PIER

4.6.1 Location.

The Naval Air Station (NAS), Whidbey Island Seaplane Base Pier is located at 48°17'05"N 122°37'20"W. It is situated on the west side of Crescent Harbor near the north end of Saratoga Passage (Figure 22). NAS Whidbey Island is composed of two main installations. The first, Ault Field, is the operating Naval Air Station. It is located approximately three nmi north-northwest of the Seaplane Base on the west side of Whidbey Island. The second installation is the Seaplane Base. The facility was initially constructed to accommodate the many seaplanes that were stationed at NAS Whidbey Island in the 1950’s. The pier was used as a mooring for a seaplane tender that was stationed on Crescent Harbor to service the seaplanes. With the phasing out of seaplanes, the pier is now used primarily as a mooring facility for visiting U.S. Coast Guard cutters and buoy tenders, and minesweepers of the Canadian Armed Forces. This evaluation addresses the Seaplane Base Pier only.

Figure 22. Location of NAS Whidbey Island Seaplane Base Pier on Crescent Harbor at the north end of Saratoga Passage.

4.6.2 Port Facilities.

The Seaplane Base Pier is approximately 550 ft (168 m) long (Figure 23). The west end of the pier extends approximately 50 ft (15 m) over the shore line, so the usable, mooring portion of the pier is less than it's total length. The pier extends into Crescent Harbor on an orientation of roughly 080°T. Charted water depths on the north side of the pier are 25 to 26 ft (7.6 to 7.9 m). Depths on the south side are 18 to 24 ft (5.5 to 7.3 m), with the shallower depths near the west end of the pier. Deck height of the pier is 17 ft above mean lower low water. The decking on the pier is in poor condition due to weathering and general deterioration. As of May 1996, funding has been allocated for replacement of the decking, but the completion date for the project had not been established.

Figure 23. Seaplane Base Pier at NAS Whidbey Island.

There are no specified anchorage areas in Crescent Harbor or northern Saratoga Passage. NAS Whidbey Island does not have a tug boat complement.

4.6.3 Adjacent Topography.

As shown in Figure 24, several sites near the Seaplane Base Pier have elevations exceeding 200 ft. One area northeast and east of the pier has elevations exceeding 400 ft. Saratoga Passage, which passes between Camano Island and Whidbey Island south-southeast of the Seaplane Base provides a channel for southeasterly winds to reach the pier.

Figure 24. Topography adjacent to the Seaplane Base Pier at NAS Whidbey Island.

4.6.4 Normal and Extreme Conditions at the Port.

NAS Whidbey Island experiences different weather conditions than most of the other sites addressed in this study. Whidbey Island’s location at the east end of the Strait of Juan de Fuca routinely exposes it to relatively cool, marine air that passes eastward through the Strait. Whidbey Island is surrounded by cool water that acts as a moderating influence on temperatures. Because of these two factors, NAS Whidbey Island experiences afternoon summer temperatures that can be five to ten degrees cooler than those in most areas around Puget Sound. The temperature differences can also occur between locations on the island. Due to westerly flow from the Strait of Juan de Fuca, on summer afternoons it is not uncommon for the east side of the island to have temperatures that are several degrees warmer than those on the west side. The moderating influence of the surrounding water also make Whidbey Island less likely to experience the colder winter temperatures that are observed by stations only a few miles inland.

4.6.4.1 Wind.

Prevailing wind directions at Whidbey Island vary with the season. During late autumn, winter, and early spring, prevailing winds are southeasterly. Due to the influence of the surrounding topography, winds that are southwesterly in southern Puget Sound and southerly in mid-Puget Sound reach Whidbey Island as southeasterly. Pre-frontal southeasterly winds can be quite strong, often reaching gale force (34-47 kt). Storm force (³48 kt) winds are only rarely observed. If a low pressure system moves onshore into southwestern British Columbia or western Washington north or east of Whidbey Island, strong westerly winds are common in the pressure gradient behind the system. Such winds may quickly reach gale force (34-47 kt) following the passage of the low. The strong winds are usually not long lasting as they abate rapidly when the pressure gradient eases as the transient low pressure center moves away from the Puget Sound region. Southeasterly flow usually returns to the area within 24 hours. The prevailing wind at NAS Whidbey Island (Ault Field) is southeasterly 10 to 12 kt from October through March. Because of the exposure of the Seaplane Base, southeasterly wind speeds can be as much as 5 to 10 kt greater than those recorded at Ault Field.

Summer winds are mostly light to moderate. A typical day has light and variable winds during early morning shifting to westerly 10 to 18 kt by early afternoon as daytime heating draws marine air in from the Strait of Juan de Fuca. The westerly winds usually last until late evening before abating.

4.6.4.2 Waves.

Waves are not a problem at the Seaplane Base Pier for vessels moored to its north side. Vessels moored to the south side are fully exposed to waves that move northward through Saratoga Passage. The highest waves would likely occur only during autumn, winter, and spring months. Lilly’s 1983 publication Marine Weather of Western Washington contains a compilation of potential wave generation values for specific wind directions and speeds in Puget Sound. Wave heights for the water area adjacent to the Seaplane Base Pier have been excerpted from that publication and are listed in Table 13. The specific point for which calculations were made is located two nmi west of Rocky Point on Camano Island (Figure 22).

Table 13. Wave heights (in feet) in Saratoga Passage for listed wind direction, speeds and duration periods. The specific point for which calculations were made is located two nmi west of Rocky Point on Camano Island (Figure 22). Adapted from Lilly (1983).

	South-Southeast Wind
	Duration in hours
Wind Speed (kt)	1	2
10	0.3	0.6
20	1.7	1.7
30	2.8	2.8
40	3.8	3.8
50	5.0	5.0
60	6.1	6.1
70	7.4	7.4

4.6.4.3 Visibility.

Visibility records are not maintained at NAS Whidbey Island’s Seaplane Base. They are maintained at the Naval Pacific Meteorology and Oceanography Facility (NPMOF) at NAS Whidbey Island (Ault Field). As previously stated, Ault Field is located on the west side of the island approximately three nmi north-northwest of the Seaplane Base. Because Ault Field is in an exposed location at the east end of the Strait of Juan de Fuca, it is subject to advection fog episodes that may not affect the Seaplane Base. During summer and early autumn, it is not uncommon for locations on the west side of the island to have low cloud ceilings and reduced horizontal visibility when the east side of the island has sunshine and good visibility. The Seaplane Base does experience fog; it is just a less frequent occurrence. When advection fog does occur, conditions at the Seaplane Base will normally improve more rapidly than conditions at Ault Field. If the fog is early morning radiation fog, conditions at Ault Field and the Seaplane Base will improve at roughly the same rate as daytime heating dissipates the fog.

Figure A-14 in Appendix A depicts the average number of days when cloud ceilings of 200 ft or less or visibility of ¼ mi or less are observed at Ault Field. Table 14 lists the mean number of days with fog (visibility less than seven nmi) at NAS Whidbey Island (Ault Field).

Table 14. Mean number of days that fog is observed at NAS Whidbey Island (Ault Field). Adapted from Federal Climate Complex, Asheville (1995).

JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
10	10	8	7	6	8	10	14	15	17	11	10	126

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4.6.4.4 Precipitation.

As can be seen in Figure A-9, most of Whidbey Island is located within the 20-inch average annual rainfall contour in the rain shadow of the Olympic Mountains. The 20-inch contour is located approximately over the location of the Seaplane Base Pier, while NAS Whidbey Island (Ault Field) is located in an area that receives less than 20 inches. Precipitation records are not maintained at the Seaplane Base, but records are kept by NPMOF at Ault Field. Although the Seaplane Base may receive slightly more precipitation than NAS Whidbey Island, the totals for NAS Whidbey Island are a very close approximation of conditions at the Seaplane Base. Figures A-10 and A-11 in Appendix A present the average monthly and annual precipitation totals for NAS Whidbey Island in comparison with other locations farther south in Puget Sound.

In addition to liquid forms of precipitation, Whidbey Island also receives periodic snowfalls during the winter season. Heavy snowfalls are uncommon. According to NPMOF Whidbey Island (1995), maximum monthly accumulations are as follows: November, 13.0 in; December, 12.6 in; January, 17.4 in; February, 10.2 in; and March, 15.5 in. Figure A-16 in Appendix A depicts the average snowfall amounts received at NAS Whidbey Island and other locations on Puget Sound during the months of November through March.

4.6.4.5 Currents.

Currents in Crescent Harbor are mostly weak and variable. Currents in Saratoga Passage south of the Seaplane Base are normally in the one-half to one kt range, with a maximum flow of less than two kt. The direction of the current is mostly tide dependent, but occasionally may be wind driven during periods of minimal tidal change and strong winds.

4.6.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.6.5.1 Strong Southeasterly Winds.

The primary hazard at the Seaplane Base is strong southeasterly winds. The south side of the pier is exposed to winds and waves as they move northward through Saratoga Passage. According to NPMOF Whidbey Island (1995), a 2.5 to 3.0 mb north-south pressure gradient between Seattle and Bellingham (higher pressure at Seattle) will produce small craft velocities (20-33 kt sustained wind) at Whidbey Island. The same document states that reported wind speed at NAS Whidbey Island (Ault Field) is not representative of wind at the Seaplane Base during intervals with east or southeasterly wind. When sustained speed is 15 kt or above at Ault Field, the Seaplane Base wind will be of small craft force (20-33 kt).

The guidelines used by operational forecasters at NWSFO, Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region, including Whidbey Island, are detailed in Section 1.2.1 of Appendix A.

4.6.5.2 Strong Westerly Winds.

Strong, westerly winds may follow the passage of a strong cold front or low pressure system as it moves inland. The primary indicator of strong westerly winds is the strength of the pressure gradient behind the low or front. If the pressure gradient from Hoquiam, WA to Ephrata, WA is seven mb, winds of small craft velocities (³20 kt sustained wind) will occur. If the same gradient exceeds nine mb, winds of gale force (34-47 kt) are likely for a two to four hour duration (NPMOF Whidbey Island, 1995).

4.6.5.3 Strong Northerly Winds.

While not common (most northerly winds are blocked by terrain), strong northerly winds may follow the passage of an intense cold front as the cold continental polar air flows southward through the Fraser River Valley into the northern part of Puget Sound. The most reliable indicators of a forthcoming strong Arctic front are the forecasts described in Section 4.6.5 above. One such event is described in Section 6.1.5 of Appendix A.

4.6.6 Protective/Mitigating Measures.

4.6.6.1 Vessels Moored to Pier.

Ships moored at the NAS Whidbey Island Seaplane Base should ensure that mooring lines are secure and tended during periods of strong winds. All loose gear and debris should be stowed in a secure location. During late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind situation during cool or cold temperature conditions.

4.6.6.2 Arriving/Departing Vessels.

As previously stated in Section 4.6.5.1, because of a difference in exposure, southeasterly winds at the Seaplane Base Pier are higher than those reported by NAS Whidbey Island (Ault Field). In some situations, the difference can be as much as 10 to 15 kt. Commanding officers should be aware of the difference, and expect stronger winds in Saratoga Passage and at the pier than those reported by Ault Field.

Table 15 - Summary of Hazardous Environmental Conditions for NAS Whidbey Island Seaplane Base Pier.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. SE’ly Winds/Waves.

* Southerly winds over Puget sound reach Whidbey Island as southeasterlies. Because of a difference in exposure, observed wind velocities reported by NAS Whidbey Island (Ault Field) may be 10 to 15 kt lower than those occurring at the Seaplane Base.

* Primarily a late autumn, winter and early spring Puget event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind warnings are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of low pressure systems and/or frontal systems as they approach the Sound region from the Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound Region one after the other, with only brief interruptions between events.

(1) Vessels moored to Seaplane Base Pier.

(2) Arriving/departing vessels.

(3) All locations/situations.

1.a. Strong southeasterly winds are the most hazardous condition at the pier.

* Properly moored vessels should experience little difficulty. Loose gear should be stowed.

* Vessels moored to the north side of the pier will be forced off of their berths. Lines should be doubled and tended to ensure a secure berth is maintained.

2.a. Southerly winds do not pose a significant problem to ships arriving at or departing from the Seaplane Base Pier.

3.a. Equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

* Equivalent wind chill temperatures can lower to the point where they are hazardous to exposed flesh. For example, a 30°F (-1°C) temperature, when combined with a wind speed of 20 to 23 kt, results in a wind chill temperature of 0°F (-18C). Appropriate precautions should be taken for all personnel working in exposed locations or on weather decks. See Table A-2 in Appendix A.

4.7 PORT OF SEATTLE

4.7.1 Location.

The Port of Seattle is located on the northeast side of Elliott Bay at 47°36'37"N 122°20'56"W (approximate mid-point of the waterfront) (Figure 25). The port is large, with pier facilities located along three nmi of Seattle's waterfront. In addition, extensive container ship and general cargo facilities are located in the southeastern part of Elliott Bay on the Duwamish Waterway, the waterways around Harbor Island, and on adjacent land (Figure 26). U.S. Navy ships visit the port mostly during local civic celebrations.

Figure 25. Location of the Port of Seattle on Elliott Bay.

Figure 26. Pier configuration and anchorages at the Port of Seattle.

4.7.2 Port Facilities.

The facilities of primary interest to this evaluation are those on or close to the Seattle waterfront, as they are the ones mostly likely to be used by visiting U.S. Navy ships (Figure 26). U.S. Navy ships are assigned to berths on an as available basis. Piers and berths are numbered in a system that increases from southeast to northwest. According to harbor authorities, preferred berths include Terminals 18, 30 and 42, and Piers 40 and 70. Aircraft carriers have been moored to Terminals 18, 25, and 30 in the past. Piers 40 and 42 are part of the Terminal 37 and Terminal 42 complexes. Pier 70 is a privately owned facility located at the north end of Seattle’s downtown waterfront. Pier 37 is occupied by the U. S Coast Guard, and is located between Terminals 30 and 37.

Mooring facilities are reported to be in good repair. Wharf specifications included in Marine Digest (1995) are listed in Table 16. Some miscellaneous piers and wharves listed in the document are not included in the table as they are specific use facilities, such as tug and barge mooring, container terminals, etc., and would not likely be used by U.S. Navy ships.

Table 16. Wharf specifications at the Port of Seattle as listed in Pacific Northwest Ports Handbook, 1995-1996, published by Marine Digest in 1995.

WHARF	BERTHS	LENGTH (FT)	HEIGHT (FT)	APRON WIDTH (FT)	WATER DEPTH (FT)
Terminal 91, Pier 90	6	295 face, 2,222 sides	18	Open	36
Terminal 91, Pier 91	6	357 face, 2,495 sides	18	Open	36
Pier 86 (Grain Pier)	1	425, 1, 440 w/dolphins	73	20	73
Terminal 48	3	600	18	50	50
Terminal 46	1	1,102	18.5	Open	50
Terminal 37	1	1,050	18	Open	50
Terminal 36 (USCG)	N/A	1,050	20	Open	34
Tank Storage Terminal, Pier 34	1	650	19	12-24	32
Terminal 30	4	2,700	18	60/open	40
Terminal 28	1	900	18	50	40
Matson Terminal 25	2	1,580	18.5	Open	50
Terminal 25 South	1	468	17	18/Open	12-25
Riedel Environmental Services Dock	1	393, 740 w/dolphins	20	Open	11-18
Seattle Intl. Terminal 18	8	6,049	18	Open	40/50
Pier 15	2	580 E/540 W	19	Open	30 to 35

Although U.S. Navy ships do not normally anchor in Elliott Bay, several anchorages are available. Local authorities state that each anchorage has a mud bottom with good holding qualities. Depths in the anchorages vary from 100 to 400 ft (30.5 to 122 m). The anchorages include Smith Cove West, Smith Cove East (a small, single ship anchorage), Elliott Bay West and Elliott Bay East. Each area is identified on Figure 26.

According to harbor authorities, no pilot is ever required by the port for U.S. Navy ships; pilots are used only if the ship requests one. Pilots are often requested during the salmon gill net season to assist in navigation through the net sets. Tug boats to 6,000 hp are readily available in sufficient quantity to handle any request. The port also has two 8,000 hp tugs, but they are assigned to the Strait of Juan de Fuca to work with super-tanker traffic. To ensure communication between the ship and tug is understood, a civilian pilot is recommended by local harbor authorities any time a civilian tug is used by a U.S. Navy ship.

4.7.3 Adjacent Topography.

The topography adjacent to the Port of Seattle is depicted in Figure 27. As the figure shows, the terrain surrounding the Port is hilly, with higher elevations exceeding 400 ft above mean sea level. The elevations of primary importance to the Port of Seattle lie north and south of Elliott Bay. Two rises, Magnolia Bluff, indicated by the circled numeral “1” on Figure 27, and Queen Anne Hill, indicated by the circled numeral “2” on the same figure, offer limited protection from north and northwesterly winds at the Port. The area between the two hills is low in elevation, however, creating a channel through which northerly winds can reach the western portions of the Port. Capitol Hill, indicated by the circled numeral “3” on Figure 27, provides an effective barrier to northeasterly flow at the port. The combined effects of the terrain of South Seattle and Beacon Hill, indicated by the circled numeral “4” on Figure 27, cause southeast clockwise through southwesterly winds to reach the eastern portions of the Port of Seattle as southerlies.

Figure 27. Topography adjacent to the Port of Seattle.

4.7.4 Normal and Extreme Conditions at the Port.

4.7.4.1 Wind.

Ships moored at the Port of Seattle are minimally affected by wind, although velocities may reach 60 to 70 kt in a very strong storm. The most hazardous wind directions at the port are from southeast clockwise to southwest. Topography south of the port in West Seattle usually causes winds from southeast clockwise to southwest to turn so they reach the easternmost piers as southerly. Southwesterly winds reach the westernmost piers as southwesterly, however. Local authorities state that an occasional northeast wind is experienced during winter, but it is not common. During summer afternoons, a northwest wind to 20 kt is commonly observed (sea breeze effect). As shown in Figure 27, valleys between the significant hills in the area create funneling effects and amplify northerly winds at the Smith Cove/Pier 90/91 area of the port. On occasion, the pilots will decline to move a ship in the Duwamish Waterway during strong winds because the lack of maneuvering room in the restricted waterway and relatively slow headway could create difficult ship control problems.

4.7.4.2 Waves.

Waves are not a significant problem at the port. The promontory on which West Seattle is located effectively protects the Seattle waterfront from most wave motion. The westernmost piers have greater exposure to southerly winds and waves. Ships arriving at or departing from the Port of Seattle will have to traverse the more exposed waters of Puget Sound where wave motion would be the greatest.

Lilly’s 1983 publication Marine Weather of Western Washington contains a compilation of potential wave generation values for specific wind directions and speeds in Puget Sound. Wave heights for the water area west of the Port of Seattle have been excerpted from that publication and are listed in Table 17. The specific point for which calculations were made is located 0.7 nmi west of West Point (Figure 25).

Table 17. Wave heights (in feet) in Puget Sound for listed wind directions, speeds and duration periods. The specific point for which calculations were made is located 0.7 nmi west of West Point. Adapted from Lilly (1983).

	South Wind			North Wind
	Duration in hours			Duration in hours
Wind Speed (kt)	1	2	3	1	2	3
10	0.3	0.8	0.9	0.3	0.8	1.2
20	1.8	2.1	2.1	1.8	2.7	2.7
30	3.2	3.5	3.5	3.2	4.2	4.2
40	4.8	4.8	4.8	4.8	5.8	5.8
50	6.3	6.3	6.3	6.7	7.6	7.6
60	7.7	7.7	7.7	8.6	9.4	9.4
70	9.3	9.3	9.3	11.0	11.0	11.0

4.7.4.3 Visibility.

Like most other locations on Puget Sound, visibility reductions are most common during early morning hours. Fog occurrence is highest during the months of September and October. Table 18 lists the mean number of days with fog at Portage Bay (approximately 2½ nmi northeast of the Seattle waterfront on the waterway between Lake Union and Lake Washington¾see Figure 25) and SEATAC Airport (approximately ten nmi south of Seattle’s waterfront). Table 18 lists the mean number of days with fog (visibility less than seven nmi) at SEATAC Airport and Portage Bay. The elevation of SEATAC is 450 ft above mean sea level (msl), so SEATAC’s visibility would occasionally be restricted by low clouds that would not hamper visibility at sea level on the Seattle waterfront. Note that Portage Bay’s occurrence rate is significantly less than that at SEATAC Airport. Since Portage Bay is located approximately three nmi from the waters of Puget Sound, it is to be expected that the site would experience fewer fog days than sites located directly on Puget Sound.

Table 18. Mean number of days with fog at Portage Bay and SEATAC Airport. Adapted from Federal Climate Complex, Asheville (1995).

	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
PORTAGE BAY	3	2	1	1	1	1	1	3	4	3	3	3	26
SEATAC	18	14	12	9	8	8	8	12	16	19	18	19	161

4.7.4.4 Precipitation.

As can be seen in Figure A-9 in Appendix A, Seattle is located in an area that receives an average of less than 40 inches of rain per year. Two sites relatively close to the Seattle waterfront maintain precipitation records. They are Portage Bay (approximately 2½ nmi northeast of the Seattle waterfront on the waterway between Lake Union and Lake Washington) and SEATAC Airport (approximately ten nmi south of Seattle’s waterfront). Figure A-10 in Appendix A is a chart showing monthly comparisons of average precipitation accumulations for four stations in the Puget Sound Region, including Portage Bay and SEATAC Airport. Figure A-11 in Appendix A is a chart showing the average annual precipitation totals for the same stations. Because of the Port of Seattle’s close proximity to the Portage Bay site, its average monthly precipitation profile and average yearly precipitation accumulation should closely approximate that of Portage Bay. As shown in Figure A-10 and according to Overland and Walter (1983), most of the precipitation in the Puget Sound region falls during the four-month period of November through February. The combined rainfall for the months of July and August is less than five percent of the annual total.

4.7.4.5 Currents.

Prevailing currents adjacent to the Port of Seattle are generally counter-clockwise and weak. According to a Senior Harbor Pilot at the Port, current flow is largely dependent on the water outflow from the Duwamish River/Waterway. The strongest currents, approximately one kt or so, are observed when periods of heavy river flow coincide with ebb tide. Discoloration of the water is a good indicator as to how much river flow is entering the bay. A greater discoloration indicates a stronger current. An eastward-setting current is occasionally noted along the waterfront during the onset of the flood tide.

4.7.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.7.5.1 Strong Southerly Winds.

The only identified hazard at the Port of Seattle is strong southerly winds. Although not a direct hazard to ships securely moored along the waterfront, strong winds could cause difficult ship handling situations for ships arriving or departing the port and could impact otherwise routine pierside operations. Winds of 20 kt or greater (small craft warning velocities) can create hazardous boating conditions for small boats going to/from ships in the anchorages. The guidelines used by operational forecasters at the National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.7.6 Protective/Mitigating Measures.

4.7.6.1 Vessels Moored Alongside Piers.

Ships moored at the Port of Seattle should ensure that mooring lines are secure and tended during periods of strong winds. All loose gear and debris should be stowed in a secure location. During late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind situation during cool or cold temperature conditions.

4.7.6.2 Vessels in the Anchorage(s).

Vessels using one of the four available anchorages should take all of the heavy weather precautions normally taken if strong winds exist or are forecast. Southerly winds and waves will have greatest effect in the two Smith Cove anchorages. Smith Cove West has the greatest exposure to southerly winds and waves. Smith Cove East has a more limited exposure. If strong winds exist or are forecast, a second anchor should be considered at each location to mitigate the effects of the wind and reduce the possibility of anchor dragging. Continuous position monitoring by the use of radar and sight lines is recommended.

Each of the two Elliott Bay anchorages is located in the lee of the peninsula south of the Port, so are protected from the full effects of the southerly winds. In a very strong wind event, a second anchor should be considered to mitigate the effects of the wind and reduce the possibility of anchor dragging. Continuous position monitoring by the use of radar and sight lines is recommended.

As previously discussed in Section 4.7.6.1, during late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. See Table A-2 in Appendix A for equivalent wind chill calculations.

4.7.6.3 Arriving/Departing Vessels.

Vessels arriving at or departing from the Port of Seattle should be aware that southerly winds in the more exposed areas of Puget Sound will likely be greater than that reported by the Port. The piers east of Terminal 86 and the Elliott Bay East and Elliott Bay West (Figure 26) anchorages will experience lighter winds due to the terrain effects of the West Seattle promontory south of the Port. The strongest southerly winds experienced by an inbound or outbound vessel will likely be encountered in Admiralty Inlet, along the west side of Whidbey Island (Figure 2).

4.7.6.4 Small Craft.

During periods of southerly winds, small craft operating to/from the anchorages will experience more moderate conditions if the runs are confined to the southeastern part of Elliott Bay. A specific Fleet Landing is not designated. If the Coast Guard Station at Pier 37 is utilized as a Fleet Landing, minimal wave motion should be encountered. If a very strong wind event is forecast, small craft operations should be suspended until the winds abate.

Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. See Table A-2 in Appendix A for equivalent wind chill calculations.

Table 19 - Summary of Hazardous Environmental Conditions for the Port of Seattle.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* Topography south of the Port turns southeast through southwest winds so that they reach most of the Port as southerly, but southwesterly winds reach the westernmost piers as southwesterly.

* Waves of 8 to 10 ft or higher are possible in Puget Sound adjacent to Elliott Bay, but waves east of Terminal 86 are reduced by the lack of fetch to the south.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind warnings are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of approaching low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored to Piers.

(2) Vessels in the Smith Cove and Elliott Bay anchorages.

(3) Arriving/departing vessels.

(4) Small boat operations.

(5) All locations/situations.

1.a. Properly moored vessels should experience little difficulty. Lines should be tended and doubled as necessary to prevent excessive motion. Loose gear should be stowed.

2.a. Winds and waves will have greatest effect in the two Smith Cove anchorages.

* Each of the two Elliot Bay anchorages is located in the lee of the peninsula south of the Port, so are protected from the full effects of the southerly winds. Smith Cove West has the greatest exposure to southerly winds and waves. Smith Cove East has a more limited exposure. If strong winds exist or are forecast, a second anchor should be considered at each location to mitigate the effects of the wind and reduce the possibility of anchor dragging. Continuous position monitoring by the use of radar and sight lines is recommended.

3.a. Southerly winds do not pose a significant problem to ships arriving at or departing from the Port of Seattle.

* Ships arriving at the Port of Seattle from the Strait of Juan de Fuca will likely encounter Puget Sound’s strongest winds in Admiralty Inlet. The same is true for departing vessels.

4.a. Runs to/from the anchorages should experience little difficulty until winds in Elliott Bay approach small craft warning velocity (³20 kt).

* Winds will affect the more exposed runs to the Smith Cove Anchorages first. If a strong event is occurring or forecast, boating operations should be suspended until the winds abate.

5.a. Equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

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4.8 PORT OF TACOMA

4.8.1 Location.

The Port of Tacoma is located at the southeast end of Commencement Bay at approximately 47°16'48"N 122°25'00"W (Figure 28). Army reservists are the primary military users of the Port of Tacoma, but an occasional U.S. Navy ship will visit the port during civic celebrations.

Figure 28. Location of the Port of Tacoma on Commencement Bay.

4.8.2 Port Facilities.

The port is comprised of several waterways. The one of interest to this evaluation is the Blair Waterway (Figure 29). The Pierce County Terminal, at the head of Blair Waterway, is used by Military Sealift Command (MSC) ships. The terminal has two berths with a total of 1,420 ft of berthing space. Dock height is 22 ft. Alongside depth is 45 ft. The 11^th street bridge crosses the Blair Waterway approximately 1,500 yd southwest of its mouth. The usable channel width under the bridge is 150 ft.

Two large pre-positioned MSC ships are assigned to Tacoma and are anchored in Commencement Bay. Their position is indicated by the letters "MSC" on Figure 29. The ships have 106 ft (32.3 m) beams, and are kept clear of the waterways so as not to adversely impact maritime traffic.

Figure 29. Configuration of the Port of Tacoma.

A designated anchorage area is charted in Commencement Bay approximately 1,600 yd (1,463 m) northwest of the mouth of the Blair Waterway. The position of the anchorage is indicated by the circled letter “A” on Figure 29. Charted depths range from 59 ft (18 m) to over 250 ft (76 m). The bottom of the anchorage is mostly mud.

4.8.3 Adjacent Topography.

The Port of Tacoma is located between elevations exceeding 200 ft (61 m) northeast and southwest of the port (Figure 30). The area south and southeast of the port is mostly low-lying, providing a channel for southerly winds to reach the port.

Figure 30. Topography adjacent to the Port of Tacoma.

4.8.4 Normal and Extreme conditions at the Port.

4.8.4.1 Wind.

Winds, although strong at times during winter, do not pose a significant problem to ships properly moored alongside piers at the Port of Tacoma. The strongest winds are south to southwesterly, occurring in pre-frontal conditions as transient low pressure systems approach the coast of Washington. Strong north or northeast winds are uncommon.

4.8.4.2 Waves.

The location of the Port of Tacoma at the south end of Puget Sound precludes any significant effect of wave motion at the port in general, and specifically at the head of Blair Waterway where Military Sealift Command ships usually moor. Ships arriving at or departing from the Port of Tacoma will have to traverse the more exposed waters of Puget Sound and Commencement Bay, however. Lilly’s 1983 publication Marine Weather of Western Washington contains a compilation of potential wave generation values for specific wind directions and speeds in Puget Sound. Wave heights for the water area adjacent to the Port of Tacoma have been excerpted from that publication and are listed in Table 20. The specific point for which calculations were made is located 1.2 nmi west-northwest of Brown Point in the outer portion of Commencement Bay (Figure 28).

Table 20. Wave heights (in feet) for the outer portion of Commencement Bay for the listed wind direction, speeds and duration periods. The specific point for which calculations were made is located 1.2 nmi west-northwest of Brown Point in the outer portion of Commencement Bay. Adapted from Lilly (1983).

	Northeast Wind
	Duration in hours
Wind Speed (kt)	1	2
10	0.3	0.7
20	1.8	2.0
30	3.2	3.2
40	4.4	4.4
50	5.8	5.8
60	7.0	7.0
70	8.4	8.4

4.8.4.3 Visibility.

Visibility records are not maintained at Tacoma. The closest observation site near Puget Sound is SEATAC Airport, approximately 10 nmi north-northeast of Commencement Bay. Records are also maintained at McChord Air Force Base (AFB), approximately 10 nmi south-southwest of Tacoma’s waterfront. Except for the difference in elevation (SEATAC has an elevation of 450 ft above msl), the Port of Tacoma’s visibility profile should approximate that of SEATAC. SEATAC’s visibility would occasionally be restricted by low clouds that would not hamper visibility at sea level at the Port of Tacoma. The elevation of McChord AFB is 321 ft so the same qualification may apply. Table 21 lists the mean number of days with fog (visibility less than seven nmi) at McChord AFB and SEATAC Airport.

Table 21. Mean number of days with fog (visibility less than seven nmi) at McChord AFB and SEATAC Airport. Adapted from Federal Climate Complex, Asheville (1995).

	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC	ANN
MCCHORD AFB	19	16	13	10	7	6	7	11	17	20	19	20	165
SEATAC	18	14	12	9	8	8	8	12	16	19	18	19	161

4.8.4.4 Precipitation.

Figure A-9 in Appendix A depicts the average annual rainfall amounts for the Puget Sound region. In the figure, the 40-inch contour extends across the Port of Tacoma waterfront. Precipitation records are not maintained at Tacoma. Records are kept at SEATAC Airport, approximately 10 nmi north-northeast of Tacoma. The SEATAC site receives approximately the same annual precipitation total as does Tacoma. Figure A-10 and Figure A-11 in Appendix A depict the average monthly and annual precipitation accumulations for four sites in the Puget Sound area for which precipitation data are available, including SEATAC Airport. Olympia, Portage Bay (in Seattle) and NAS Whidbey Island are also depicted. Since the total annual precipitation amounts are approximately the same for Tacoma as for SEATAC, the monthly profile for SEATAC should be representative of Tacoma. As shown in Figure A-10 and according to Overland and Walter (1983), most of the precipitation in the Puget Sound region falls during the four-month period of November through February. The combined rainfall for the months of July and August is less than five percent of the annual total.

4.8.4.5 Currents.

Prevailing currents at the Port of Tacoma and in Commencement Bay are weak and variable. The Puyallup River passes through the port via the Puyallup Waterway. It creates a weak northwesterly-setting current near the mouth of the Waterway, but the current is largely diffused in the expanse of Commencement Bay. The river outflow increases and creates stronger current flow during periods of heavy precipitation and/or snow melt in the Puyallup River watershed.

4.8.5 Indicators of Hazardous Weather Conditions.

The most reliable sources of information on forthcoming strong winds are the forecasts and warnings issued by the U.S. Navy and National Weather Service. Twice daily, 24-hour weather forecasts for the inland waters of western Washington, including Puget Sound, Hood Canal, Admiralty Inlet and other marine areas are issued by the Naval Pacific Meteorology and Oceanography Facility (NPMOF), Whidbey Island, and disseminated by AUTODIN to AIG 7740 (NPMOF Whidbey Island, 1995). In addition, NPMOF Whidbey Island issues wind warnings as needed, which are also disseminated via AUTODIN to AIG 7740. The National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle also issues timely weather forecasts and warnings for inland waters that are broadcast via VHF 162.55 MHz and broadcast media (radio/television). See Appendix B.

4.8.5.1 Strong South to Southwesterly Winds.

The only identified hazard at the Port of Tacoma is strong south to southwesterly winds. Although not a direct hazard to ships that are securely moored, strong winds could cause difficult ship handling situations for ships arriving or departing Blair Waterway and could impact otherwise routine pierside operations. The guidelines used by operational forecasters at the National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle to forecast the onset of strong southerly winds in the lowlands of the Puget Sound region are detailed in Section 1.2.1 of Appendix A.

4.8.6 Protective/Mitigating Measures.

4.8.6.1 Vessels Moored at the Head of Blair Waterway.

Ships moored at the Port of Tacoma should ensure that mooring lines are secure and tended during periods of strong southerly winds. All loose gear and debris should be stowed in a secure location. During late autumn, winter, and early spring, strong winds can cause equivalent wind chill temperatures that are hazardous to exposed flesh. Personnel working on weather decks should be aware of the equivalent wind chill factor and take appropriate precautions when indicated. Table A-2 in Appendix A lists equivalent wind chill temperatures for various wind and temperature combinations. It should be referenced in any strong wind situation during cool or cold temperature conditions.

4.8.6.2 Arriving/Departing Vessels.

Southerly winds in Puget Sound north of Browns Point will likely be stronger than those experienced in the Blair Waterway at the Port of Tacoma. Velocities will increase in the narrower passages throughout the Sound. The strongest southerly winds experienced by an inbound or outbound vessel will likely be encountered in Admiralty Inlet, along the west side of Whidbey Island (Figure 2).

Table 22 - Summary of Hazardous Environmental Conditions for the Port of Tacoma.

HAZARDOUS CONDITION

INDICATORS OF POTENTIAL HAZARDS

VESSEL LOCATION/ SITUATION AFFECTED

EFFECT - PRECAUTIONARY/ EVASIVE ACTIONS

a. S’ly Winds/Waves.

* Primarily a late autumn, winter and early spring event. Uncommon in summer.

* Winds of small craft velocity (20-33 kt) occur frequently, with gale force (34-47 kt) occasionally observed. Storm force (³48 kt) winds occur only rarely.

* The Port of Tacoma is well protected from waves. The moorage at the head of Blair Waterway is almost totally protected from wave motion.

Advance Warning

* Twice daily forecasts for Puget Sound are issued by NPMOF Whidbey Island and sent by AUTODIN to AIG 7740. Wind are issued as necessary and sent to AIG 7740.

* Forecasts and warnings for Puget Sound and other inland waters are broadcast 24-hours a day by NWSFO Seattle on NOAA Weather Radio VHF 162.55 MHz.

* Southerly winds can be expected in advance of approaching low pressure systems and/or frontal systems as they approach the Puget Sound region from the Pacific Ocean.

* The strongest winds are normally associated with lows approaching from the southwest or moving northward along the Oregon coast.

Duration

* Low pressure systems may occur as a “family” of two or more storms which approach the Puget Sound region one after the other, with only brief interruptions between events.

(1) Vessels moored in the Blair Waterway.

(2) Arriving/departing vessels.

(3) All locations/situations.

1.a. Properly moored vessels should experience little difficulty. Lines should be tended, and doubled when necessary to prevent excessive motion. Loose gear should be stowed.

2.a. Southerly winds do not pose a significant problem to ships arriving at or departing from the Port of Tacoma.

* Caution should be exercised when navigating the length of the relatively narrow Blair Waterway.

* Ships arriving at the Port of Tacoma from the Strait of Juan de Fuca will likely encounter Puget Sound’s strongest winds in Admiralty Inlet.

3.a. The equivalent wind chill temperature (temperature combined with wind) must be considered during periods of cold weather.

REFERENCES

Defense Mapping Agency Hydrographic/Topographic Center (DMAHTC), 1993: Puget Sound Fleet Guide. Published by the Defense Mapping Agency Hydrographic/Topographic Center, Bethesda, MD.

Federal Climate Complex, Asheville, 1995: International Station Meteorological Climate Summary. Version 3.0, March 1995. Jointly produced by Fleet Numerical Meteorology and Oceanography Command Detachment, National Climatic Data Center, and USAFETAC OL-A. Prepared under the authority of Commander, Naval Meteorology and Oceanography Command. NOAA Support provided by Environmental Services Data and Information Management Program.

Harris, G. H., 1954: The Surface Winds over Puget Sound and the Strait of Juan de Fuca and their Oceanographic Effects. University of Washington, Seattle, WA.

Kotsch, W. J., 1983: Weather for the Mariner, Third Edition. Naval Institute Press, Annapolis, MD.

Lilly, Kenneth E., Jr., 1983: Marine Weather of Western Washington. Published by Starpath, Seattle, Washington.

Marine Digest, 1995: Pacific Northwest Ports Handbook. Published by Marine Digest, P.O. Box 3905, Seattle, WA 98124.

Mass, C. F., S. Businger, M. D. Albright and Z. A. Tucker, 1995: A windstorm in the lee of a gap in a coastal mountain barrier. Monthly Weather Review, Vol. 123, No. 2, February 1995, pp 317-331.

Maunder, W. J., 1968: Synoptic weather patterns in the Pacific Northwest. Northwest Science, 42. pp 80-88.

National Weather Service, undated: Global Maritime Distress and Safety System (GMDSS). Pamphlet prepared by the National Weather Service for the National Oceanic and Atmospheric Administration, U.S. Department of Commerce.

Naval Pacific Meteorology and Oceanography Command Detachment (NPMOCD) Whidbey Island, 1995: Local Area Forecasters Handbook. Prepared under the authority of Commander, Naval Meteorology and Oceanography Command, Stennis Space Center, MS 35922-5001.

Offley, Ed, 1996a: Newspaper article headlined: Wave of change hits Bremerton’s ever-expanding naval shipyard. Published by the Seattle Post-Intelligencer, Seattle, WA.

, 1996b: Newspaper article headlined: 19 military projects seek funds. Published by the Seattle Post-Intelligencer, Seattle, WA.

Overland, J. E., M. H. Hitchman, and Y. J. Han., 1979: A Regional Surface Wind Model for Mountainous Coastal Areas. NOAA Technical Report ERL 407-PMEL 32. Pacific Marine Environmental Laboratory, Seattle, Washington.

Overland, J. E. and B. A. Walter, Jr., 1981: Gap winds in the Strait of Juan de Fuca. Pacific Marine Environmental Laboratory, Seattle, Washington. Monthly Weather Review, Vol. 109, No. 10, October 1981, pp 2221-2233.

, 1983: Marine Weather of the Inland Waters of Western Washington. Pacific Marine Environmental Laboratory, Seattle, Washington.

Palmen, E. and C. W. Newton, 1969: Atmospheric Circulation Systems. Their Structure and Physical Interpretation. International Geophysics Series, Volume 13. Published by Academic Press, New York and London.

Reed, Richard J., 1980: Destructive winds caused by an orographically induced mesoscale cyclone. Bulletin of the American Meteorological Society, Vol. 61, No. 11, November 1980, pp 1346-1355.

U.S. Coast Guard, 1991: National Search and Rescue Manual, Volume I: National Search and Rescue System. COMDTINST M16120.5A. Published jointly by the U.S. Coast Guard, Washington, DC 20953-0001 and The Joint Chiefs of Staff, Washington, DC 20318-0200.

U.S. Department of Commerce, 1986: NODC’s Water Temperature Guide to the Pacific Coast. Brochure prepared by National Oceanographic Data Center; National Environmental Satellite, Data, and Information Service; National Oceanic and Atmospheric Administration, Washington, DC 20235

1992: United States Coast Pilot 7, Pacific Coast: California, Oregon, Washington, and Hawaii. Published by the Coast and Geodetic Survey (N/CG2211), National Ocean Service, National Oceanographic and Atmospheric Administration, Rockville, MD 20852-3806.

APPENDIX A

SEASONAL WEATHER PATTERNS IN THE PUGET SOUND REGION

1.0 GENERAL

1.1 Typical Weather Patterns.

Four basic synoptic situations are identified as being representative of typical weather patterns in the Puget Sound region (Overland and Walter, 1983). They are shown in Figure A-1.

Figure A-1. Typical weather patterns affecting Puget Sound weather.

Figure A-1a and A-1b depict the primary storm threat patterns for the Puget Sound region. The two patterns are most commonly observed in the months of October through mid-April. In Figure A-1a, the pressure pattern designated as Low Type 1 is associated with a large low pressure system in the Gulf of Alaska. The low pressure system is usually accompanied by a series of cold fronts. The low pressure center normally rotates slowly about its semi-permanent position within the Gulf of Alaska. The associated cold frontal systems rotate about the center of the low and move rapidly eastward in the strong westerly flow around the low’s southern periphery. The warm air mass ahead of the front is usually small in extent by the time the front nears the coast. Consequently, warm fronts are often weak and diffuse, and do not have a significant effect on the weather of the region (Overland and Walter, 1983).

The surface features of the cold front often rapidly approach the coast and then slow as the coastal features are encountered, while the upper level features continue to move rapidly over Puget Sound. As a result, the severity of the weather associated with the front is not always as great over Puget Sound as it is when the storm system is over the Pacific Ocean (Overland and Walter, 1983). Coastal conditions are, as a rule, much more harsh than those in the Sound. Because of the effects of the continent and the mountain ranges, it is often difficult to forecast the timing and severity of frontal features over Puget Sound merely by extrapolating the speed of the storm while it is over open water. The average number of days per month with various synoptic weather patterns is included in Table A-1.

Table A-1. Number of days per month with synoptic weather patterns Low Type 1, Low Type 2, High Type 1 and High Type 2. Adapted from Maunder (1968) as presented by Overland and Walter (1983).

WEATHERPATTERN	MONTH
WEATHERPATTERN	J	F	M	A	M	J	J	A	S	O	N	D	YEAR
Low Type 1	14	10	7	12	7	4	5	5	5	14	10	13	106
Low Type 2	9	4	11	10	6	6	4	7	6	4	13	11	91
High Type 1	4	2	3	0	1	1	1	1	3	6	3	4	29
High Type 2	3	14	8	7	13	15	16	14	16	5	2	3	116

Low Type 2 in Figure A-1b depicts a second type of storm. The synoptic pattern is characterized by small disturbances that form in the central Pacific Ocean and move across the Pacific on a northeast trajectory. Some may pass parallel to the coastline on a northerly heading or cross over British Columbia. Such extratropical cyclones can rapidly intensify as they propagate northward while seaward of the Oregon and Washington coastline (Overland and Walter, 1983). If they intensify sufficiently, they can produce some of the most severe weather encountered in Puget Sound.

As related by Overland and Walter (1983), at some time during most winters, an upper-level blocking ridge of high pressure develops over northwest Canada. See High Type 1 in Figure A-1c. If the high pressure cell is strong enough, it forces intensely cold, dense, Arctic air southward through the Fraser River Valley, a gap between the Coastal Range of western British Columbia and the Cascade Mountains (Figure 1). Such cold outbreaks are preceded by the southward movement of an Arctic front through British Columbia into Puget Sound. The event is usually triggered by the movement of a low pressure system toward the Washington coast, which establishes a strong east-to-west pressure gradient between the low and the cold high pressure cell over British Columbia. While most Arctic outbreaks are moderate in intensity, with their effects felt only as far south as the Bellingham area of western Washington, some are quite strong. Strong (³49 kt/25 m s^-1) outflows of “Arctic” air through the Fraser Gap into western Washington occur approximately once or twice a year (Mass, et al., 1995). The strongest winds are usually confined to an area from the Fraser River Valley to Bellingham, Washington thence southwestward across the San Juan Islands and the eastern Strait of Juan de Fuca to the north coast of the Olympic Peninsula. Extreme northeasterly wind events, during which wind speeds exceed 80 kt (40 m s^-1) occur on the average of once every five to ten years. Once the high pressure has reached Puget Sound and the initial strong push of cold air has passed, the result is usually clear skies and near- or sub-freezing temperatures over Puget Sound until the next extratropical storm system approaches the area and pre-frontal, southerly flow again brings warmer temperatures to the region. Figure A-2 depicts the progression of a typical polar continental front through the Puget Sound region. The speed of movement of these type of fronts may vary considerably from that shown in the figure.

Figure A-2. Typical movement of an Arctic front through the Puget Sound region. Adapted from Lilly (1983).

From the end of June through August, the synoptic situation over the sound is characterized by a marine high-pressure cell that dominates the area. See High Type 2 in Figure A-1d. Although low pressure systems occasionally move through the region, their strength is lessened by the effects of the high pressure.

1.2 Wind.

Wind patterns over Puget Sound and adjacent waters vary considerably from one location to another. Each site is affected differently by the interaction of synoptic wind flow and the local topography. The differences are perhaps most pronounced during periods of south to southwest synoptic flow, which is the prevailing wind direction in late autumn, winter and early spring. In the southern part of the Sound, the winds are generally felt as southwesterly as the wind flows around the southern end of the Olympic Mountains through the Chehalis River Valley, also commonly called the Chehalis Gap (Figure 1). In the central portion of the Sound, the wind direction becomes more southerly as it passes between the Olympic and Cascade Ranges. The air flow reaches the north part of Puget Sound and Whidbey Island as southeasterly and flows out the Strait of Juan de Fuca as east-southeasterly.

Wind velocities also vary greatly from one location to another due to the enhancing or blocking effects of surrounding topography. While moderate south or southwesterly flow is usually strongest in Admiralty Inlet (Figure 5), Hood Canal (Figure 6), and in Saratoga Passage east of Whidbey Island (Figure 26), other areas may experience stronger winds in specific situations. Westerly and northwesterly flow is felt most strongly in the Strait of Juan de Fuca (Figure 2), on Whidbey Island, Admiralty Inlet, and the southern portions of Saratoga Passage.

1.2.1 Forecasting the Onset of High Winds in the Puget Sound Lowlands.

Guidelines similar to the following are used by operational forecasters at the National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle to forecast the onset of strong winds in the lowlands of the Puget Sound region. The guidelines refer to the areas outlined in Figure A-3. (Note: area C is the area northwest of area C. Lows moving into area C normally produce stronger winds over Puget Sound than those moving into area C.)

Figure A-3. Areas used in forecasting the onset of high winds in the Puget Sound lowlands by NWSFO personnel at Sand Point.

(1) 24 hours - Watch Decision Tree

a. A surface low or comma cloud with a well formed slot is located in zone “A.”

Yes - Go to b. No - No action required.

b. A 500 mb trough exists between 130°W and 140°W and extends south of 45°N and a cutoff low has not formed.

Yes - Go to c. No - No action required.

c. The 12-hour trajectory moves the center of the low inside of zone “B” and 24-hour trajectory moves into zone “C” or “C’.”

Yes - Go to d. No - No action required.

d. A split is identified in the flow from satellite loop or a secondary surface low has moved or formed to the rear of the primary circulation and is moving rapidly into the pressure field.

Yes - No action required. No - Issue a high wind watch for Puget Sound

lowlands.

(2) 18 hours - Watch Condition Decision Tree

a. Trajectory of surface low or comma cloud continues toward zones “B” and “C.”

Yes - Go to b. No - Go to d.

b. The surface low has undergone explosive deepening and is moving toward “C” or “C’.”

Yes - Go to e. No - Go to c.

c. A split in the flow or another surface low has moved into or formed to the rear, or near to and south of the initial surface low.

Yes - Go to d. No - Continue watch.

d. Cancel Watch.

e. Issue High Wind Warning for Puget Sound lowlands.

(3) 12 hours - Watch/Warning Decision Tree.

a. Surface low has moved into zone “B” and the surface low trajectory is toward “C.”

Yes - Go to b. No - Cancel watch.

b. Pressure rises on the southern Oregon coast of 2 mb or more in past three hours or less.

Yes - Go to c. No - Hold Watch.

c. Pressure falls in zone “C.”

Yes - Go to d. No - Hold Watch.

d. Does NMC surface prognosis show surface low moving into north end of Puget Sound?

Yes - Go to e. No - No action required

e. Issue High Wind Warning for Puget Sound Lowlands.

(4) Six Hour - Warning Decision Tree.

a. Does the trajectory of the surface low cross the Olympics?

Yes - Go to e. No - Go to b.

b. The surface low is east of 130°W and near or just off the Washington coast. The trajectory of the low is toward zone “C.”

Yes - Go to c. No - Go to d.

c. Three-hourly pressure rises in the Willamette Valley are 3.5 mb or greater.

Yes - Go to e. No - Go to d.

d. The Quillayute, WA or Salem, OR sounding shows wind speeds below 6,000 ft as southerly 40 mph or more.

Yes - Go to e. No - Cancel watch or warning.

e. Issue High Wind Warning immediately.

1.3 Waves.

Wave generation is primarily dependent on three factors: (1) wind speed, (2) the fetch length of the generation area, and (3) the length of time that the wind acts on the fetch. Water depth is also considered in some calculations. The unique shape of Puget Sound effectively limits the generation of large waves within the Sound because they are fetch limited. As shown in Figure A-4, the longest straight-line fetch distance over water within the Sound is 34 nmi between Maury Island in the south Sound to Useless Bay on the south shore of Whidbey Island (Harris, 1954). The largest wave heights in the Sound are found in the waters north of the south end of Whidbey Island. Wave height calculations for the eight specific harbor locations addressed in this study are included in the sections pertaining to each location.

Figure A-4. Straight line fetch distances within Puget Sound. Adapted from Harris (1954).

1.4 Temperature.

Surface air temperatures around Puget Sound differ by location, synoptic situation, and wind direction. Because of the moderating effects of the waters of the Sound, most land areas adjacent to the water do not normally experience hot temperatures in the summer or frigid temperatures in winter. During the summer months, afternoon temperatures at lower elevations commonly range from 68°F (20°C) to 77°F (25°C) (Overland and Walter, 1983). Maximum temperatures may reach 84°F (29°C) to 90°F (32°C) on a few days each year. Temperatures of 100°F (38°C) or higher are extremely uncommon.

In winter, lowland temperatures in Puget Sound usually range from 37°F (3°C) to 45°F (7°C) in the afternoons and 28°F (-2°C) to 41°F (5°C) at night. The temperature drops to between 19°F (-7°C) and 10°F (-12°C) on a few nights almost every winter. The coldest weather occurs during a few short outbreaks of cold, dry air from the north or east (Overland and Walter, 1983).

Equivalent Chill Temperatures (wind chill) must be considered by personnel working on weather decks or other exposed locations during the autumn, winter and spring seasons. The cooling effect of wind and temperature can result in equivalent chill temperatures that are considerably lower than the ambient air temperature on exposed flesh. Table A-2 lists equivalent chill temperatures for various temperature and wind speed combinations.

Table A-2. Wind Chill. The cooling power of the wind expressed as “Equivalent Chill Temperature” (adapted from Kotsch, 1983).

Wind Speed		Cooling Power of Wind expressed as “Equivalent Chill Temperature”
Knots	MPH	Temperature (°F)
Calm	Calm	40	35	30	25	20	15	10	5	0
3-6	5	35	30	25	20	15	10	5	0	-5
7-10	10	30	20	15	10	5	0	-10	-15	-20
11-15	15	25	15	10	0	-5	-10	-20	-25	-30
16-19	20	20	10	5	0	-10	-15	-25	-30	-35
20-23	25	15	10	0	-5	-15	-20	-30	-35	-45
24-28	30	10	5	0	-10	-20	-25	-30	-40	-50
29-32	35	10	5	-5	-10	-20	-30	-35	-40	-50
33-36	40	10	0	-5	-15	-20	-30	-35	-45	-55

Figures A-5 through A-8 present the temperature distributions for Olympia (south Puget Sound), SEATAC Airport (south-central Puget Sound), Portage Bay (north-central Puget Sound), and NAS Whidbey Island (east end of the Strait of Juan de Fuca just north of Puget Sound.

Figure A-5. Monthly temperature distribution at Olympia, Washington (46°58’N 122°54’W) based on the 43-year period

1948 through 1990. Field elevation 192 ft (59 m). Adapted from Federal Climate Complex, Asheville (1995).

Figure A-6. Monthly temperature distribution at Seattle-Tacoma International Airport (47°27’N 122°18’W) based on the

43-year period 1948 through 1990. Field elevation 450 ft (137 m).

Adapted from Federal Climate Complex, Asheville (1995).

Figure A-7. Monthly temperature distribution at Seattle (Portage Bay) (47°39’N 122°18’W) based on the 92-year period

1900 to 1992. Field elevation 20 ft (6 m). Adapted from Federal Climate Complex, Asheville (1995).

Figure A-8. Monthly temperature distribution at NAS Whidbey Island (Ault Field) (48°21’N 122°40’W) based on the

48-year period 1945 to 1992. Field elevation 46 ft (14 m). Adapted from Federal Climate Complex, Asheville (1995).

While the temperature curves are similar in profile, NAS Whidbey Island experiences summer temperatures that are four to six degrees cooler than the other three sites. The difference is largely due to the influence of westerly afternoon sea breezes blowing over the relatively cooler waters of the Strait of Juan de Fuca. SEATAC Airport and Portage Bay experience the warmest average mean summer temperatures. Olympia, at the extreme southern end of Puget Sound and the southernmost of the four sites, experiences the warmest maximum temperatures during the summer and coldest winter temperatures.

1.5 Water Temperature.

Water temperatures in Puget Sound and the Strait of Juan de Fuca vary by approximately 8 to 9°F from summer to winter. The water temperature varies slightly from location to location, with the colder temperatures found in and near the Strait. Table A-3 lists average water temperatures by month for the three locations for which data are available.

Table A-3. Average water temperatures in the Puget Sound region. Adapted from U.S. Department of Commerce (1986).

	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC
Neah Bay	45	46	47	48	50	52	53	53	52	51	49	47
Pt Townsend	44	44	46	47	49	51	53	54	53	51	50	46
Seattle	47	46	46	48	50	53	55	56	55	53	51	49

Because of the relatively cold water temperatures, survivability of personnel that are immersed in the water by falling overboard or other means, is severely jeopardized. Hypothermia resulting from immersion, either intentional or unintentional, is a life-threatening hazard that must be taken seriously. The National Search and Rescue Manual, published by the U.S. Coast Guard (1991), contains a graph depicting calm water survival times for lightly clothed, non-exercising humans in cold water. There is considerable variability associated with body size, build, fatness, physical fitness, and state of health. According to the manual, a non-swimming, average person has a life expectancy of approximately two hours in calm water with a temperature of 44°F (7°C), and four hours in calm water with a temperature of 56°F (13°C). The times could be reduced to one and two hours respectively for “fast coolers,” i.e. persons of low body weight, children, light clothing, or those who are exercising such as persons without PFDs having to swim to remain afloat.

1.6 Precipitation.

The Olympic Mountain Range is the single most important factor in precipitation distribution in northwest Washington. As a result of its effect, accumulations vary quite markedly from one location to another. The annual range of average total accumulation amounts vary from less than 15 inches in the center of the so-called “rain shadow” off the northeast coast of the Olympic Peninsula, west of Whidbey Island, to over 220 inches on the western slopes of the Olympics (Figure A-9).

As shown in Figure A-9, most of the Puget Sound region receives an annual precipitation total of less than 40 inches. Exceptions include the southwest portion of Puget Sound and the southwestern part of Hood Canal. Amounts exceeding 100 inches are located in the extreme southwestern part of the state just north of the mouth of the Columbia River, and along the Cascade Mountain Range. The greatest amounts in the Cascade range exist where the terrain is the highest, such as 120+ inches east of Bellingham (near Mount Baker), 140+ inches southeast of Tacoma (near Mount Rainier), and 140+ inches in the southeast corner of the figure (near Mount St. Helens).

Figure A-9. Average annual precipitation distribution totals for western Washington.

Precipitation contours are in inches. Adapted from Lilly (1983).

Approximately 50% of the annual precipitation for the Puget Sound region falls in the four-month period of November through February, while the combined rainfall for the months of July and August is less than five percent of the annual total (Overland and Walter, 1983). The annual cycle of precipitation for north, central and south Puget Sound is shown in Figure A-10. The effects of the rain shadow of the Olympic Mountains is reflected in the monthly amounts. The stations farther south in Puget Sound get greater precipitation amounts than the totals recorded at the more northern sites.

Figure A-10. Average monthly precipitation amounts for Olympia (south Puget Sound), Seattle-Tacoma International Airport

(central Sound), Portage Bay (central Sound), and NAS Whidbey Island (in the rain shadow of the Olympic Mountains

at the east end of the Strait of Juan de Fuca). Adapted from Federal Climate Complex, Asheville (1995).

Figure A-11 depicts the average annual precipitation accumulations for the same four stations that were depicted in Figure A-10. The figure clearly shows the effects of the rain shadow of the Olympic Mountains. NAS Whidbey Island, in the rain shadow, receives less than 40% of the average annual rainfall recorded at Olympia, a station located outside the rain shadow effects of the Olympic Range.

Figure A-11. Average annual precipitation comparisons between Olympia (south Puget Sound), Seattle-Tacoma International Airport

(central Sound), Portage Bay (central Sound), and NAS Whidbey Island (in the rain shadow of the Olympic Mountains

at the east end of the Strait of Juan de Fuca). Adapted from Federal Climate Complex, Asheville (1995).

The north Puget Sound region experiences a unique phenomenon called “the Puget Sound convergence zone.” The convergence zone is caused by the splitting of westerly airflow around the Olympic Mountains west of Puget Sound and subsequent convergence as the airflow merges east of the Olympics. Figure A-12 depicts the convergence zone’s mechanics. The convergence zone is most active following the passage of a cold front when the synoptic weather pattern brings westerly, unstable flow to the Puget Sound region, but it can form anytime westerly flow is present, including the summer season. A typical convergence zone scenario will start with the formation of a line of convective clouds extending across the Sound from the Olympic Mountains to the Cascades in the south Whidbey Island/Everett area. The zone usually moves slowly southward during the afternoon, dissipating before reaching Tacoma. There are wide variations to this scenario, however, as some convergence zones will move northward or remain stationary. Summer convergence zone activity is usually limited to late afternoon and/or early evening hours. Weather in the convergence zone area is characterized by frequent rain showers. A strong outbreak of unstable, westerly flow can cause heavy showers and/or thundershowers. In the November through March period, snow showers in the convergence zone can bring a significant amount of snow to the Everett area in a short time.

Figure A-12. Simplified depiction of the mechanics of the convergence zone process.

Adapted from Lilly (1983).

1.7 Visibility.

Visibility in the Puget Sound region is generally good (³7 nmi or more), but periods of reduced visibility are not uncommon. In general, visibility restrictions result from one of two main causes, fog and man-caused pollutants. Fog is the primary cause of visibility reduction to the point where it may hamper navigation within Puget Sound. Fog may form either in high pressure situations or low pressure situations as long as there is sufficient moisture in the air to be cooled to the point of condensation (Lilly, 1983). Fog may occur any time of the year, although some months have much higher frequencies of occurrence. Fogs occurring over Puget Sound are of two main types: radiation fog and advection fog, also called sea fog.

The most persistent fogs are radiation fogs that exist in high pressure patterns. Winds in high pressure patterns are usually light, and cloud free skies are common. These two conditions allow heat from the earth’s surface to radiate and escape, thereby cooling the lower layers of the atmosphere. As the air is cooled to its dew point temperature, condensation in the form of fog occurs. A fog layer in Puget Sound is usually 200 to 500 ft (61 to 152 m) thick (Lilly, 1983). A thin layer of fog will likely dissipate by late morning as a result of daytime heating. A thick layer may not. Typically, radiation fogs are uncommon in spring and early- to mid-summer. They increase in frequency toward the end of summer, reaching a peak in October.

Advection fog forms over the ocean when a layer of relatively warmer air moves is cooled from below by cooler water. It is common over the coastal waters of northern California, Oregon, Washington and British Columbia during summer and early autumn. It is a result of cooler, sub-surface water being brought to the surface by a process known as upwelling. If high pressure is present offshore when the fog is present, the fog is often forced eastward through the Strait of Juan de Fuca. Most often, the southward limit of the fog is Admiralty Inlet. It has been known to reach the southern part of Puget Sound, but more often than not Puget Sound proper will experience a low layer of stratus clouds (Lilly, 1983). Advection fog is also different from radiation fog in that it can persist in winds over 25 kt.

Figure A-13 shows that Olympia, Tacoma, and SEATAC Airport have markedly different occurrence trends than does Port Angeles in the eastern Strait of Juan de Fuca. The difference is due to Port Angeles being primarily affected by advection fog that is most prevalent during summer, while the Puget Sound sites are affected primarily by radiation fog. Radiation fog is most common during early autumn.

Statistics similar to those used in Figure A-13 that address heavy fog alone are not available for locations within Puget Sound north of SEATAC Airport. NPMOD Whidbey Island (1995) contains monthly climatology summaries for NAS Whidbey Island that contain statistics relating to the combined occurrences of cloud ceiling levels and visibility. Figure A-14 depicts the percent frequency of occurrence of ceilings £200 ft or visibility £1/4 mi at NAS Whidbey Island.

Figure A-13. Average number of days with heavy fog (visibility £1/4 mi) at the locations listed.

The number in parenthesis following the name of each site is the average annual number

of days when heavy fog was observed at that site. Duration is not considered.

Adapted from Lilly (1983).

NAS Whidbey Island’s location at the east end of the Strait of Juan de Fuca makes it vulnerable to visibility restrictions caused by advection fog as it moves east through the Strait. The station is affected to a lesser degree by radiation fog. As a result, the ceiling/fog frequency of occurrence line in Figure A-14 is a rough approximation of the combination of the Puget Sound lines and the Port Angeles line depicted in Figure A-13.

Figure A-14. Percent frequency of occurrence of ceilings £200 ft or visibility £1/4 mi at NAS Whidbey Island.

Adapted from NPMOD Whidbey Island (1995).

2. WINTER WEATHER

2.1 Typical Weather Patterns.

The winter season over the Puget Sound is characterized by a sequence of transiting extratropical low pressure systems that move through the Pacific Northwest. On an infrequent basis, the cycle of seemingly continuous passages of low pressure systems is interrupted by high pressure cells that may remain over the Sound for a few days to two or three weeks at a time.

The predominant weather pattern during the winter season is Low Type 1. Low Type 1 is discussed in Section 1.1 of this appendix and depicted in Figure A-1a. The cold frontal systems that are associated with the semi-permanent low pressure system in the Gulf of Alaska rotate about the center of the low and move rapidly eastward in the strong westerly flow around the low’s southern periphery. The result in Puget Sound is moderately gusty surface winds in the southerly flow preceding the front, and rain. Following frontal passage, there is usually a period of 24 to 36 hours before another front rotating about the same low pressure system begins to affect the weather of Puget Sound.

A secondary, and less frequent, weather pattern affecting Puget Sound weather, Low Type 2, is discussed in Section 1.1 of this appendix and depicted in Figure A-1b. The synoptic pattern is characterized by small disturbances that form in the central Pacific Ocean and move across the Pacific on a northeast trajectory. Those moving parallel to the coastline on a northerly heading or cross over British Columbia can rapidly intensify as they propagate northward while offshore (Overland and Walter, 1983). Some of the most severe weather encountered in Puget Sound has been produced by such storms. As related in Section 1.1 of this appendix, one such storm moved northward along the coast in December 1995, and brought sustained winds commonly exceeding 50 kt to the Puget Sound region. A ship located in Puget Sound just west of Seattle reported a gust of 78 kt (90 mph). A coastal station in Oregon reported winds of 103 kt (118 mph).

2.2 Wind.

The prevailing wind direction over Puget Sound during the winter season is south-southwesterly with an average speed of 12 kt at SEATAC Airport, and 8 kt at Olympia (Federal Climate Complex, Asheville, 1995). NAS Whidbey Island, located just north of Puget Sound, has a prevailing wind of southeasterly 11 to 12 kt. Except during periods of strong post-frontal westerly winds following the passage of a low pressure system through the area, easterly winds prevail in the Strait of Juan de Fuca during the winter season.

Strong winds are frequently experienced during the season. Velocities in excess of 20 kt are common. Gale force (34-47 kt) winds are not rare, thought they are most often observed in the northern part of the Sound where funneling between the Olympic and Cascade Mountain ranges is the strongest.

2.3 Temperature.

As shown in Figure A-5, Figure A-6, Figure A-7, and Figure A-8, the Puget Sound region experiences relatively warm temperatures throughout most of the winter season. In winter, average lowland temperatures in Puget Sound range from 37°F (3°C) to 45°F (7°C) in the afternoons and 28°F (-2°C) to 41°F (5°C) at night (Overland and Walter, 1983). The temperature drops to between 19°F (-7°C) and 10°F (-12°C) on a few nights almost every winter. The coldest weather occurs during a few short outbreaks of cold, dry air from the north or east.

2.4 Precipitation.

Precipitation in the areas with elevations below 1,500 ft is primarily liquid in the form of rain or drizzle. The effects of the rain shadow of the Olympic Mountains are most evident during the winter season. Figure A-15 depicts the average precipitation amount for each of the winter months for the sites indicated.

Figure A-15. Average precipitation totals during the months of December through March for the sites listed.

Data extracted from Federal Climate Complex, Asheville (1995).

Snowfall is not uncommon during the winter season. The total average snowfall is generally less than 10 inches per year and normally falls in the November to March period. Maximum snowfall amounts are most often recorded in January, with February and December usually recording lesser amounts. Every few years or so, snowfalls of ten inches or greater occur in the lowlands around the Sound. Unless the snowfall is followed by a period of sub-freezing temperatures after an intense cold front moves through the area, snow in the lower elevations (below 500 ft) usually melts rapidly and is gone in a day or two. Figure A-16 depicts snowfall amounts for selected sites in Puget Sound for the months of November through March.

Figure A-16. Average monthly snowfall amounts for the sites listed. Trace amounts not included. NAS Whidbey

amounts include hail. Data extracted from Federal Climate Complex, Asheville (1995).

3.0 SPRING WEATHER

3.1 Typical Weather Patterns.

Early spring weather is not significantly different from that of winter. Extratropical low pressure systems, such as those depicted in Figures A-1a and A-1b still migrate through the Pacific Northwest and cause considerable stormy weather in the Puget Sound region. By May, the strength of the upper-level westerly flow is diminished. As a result, the frequency of cyclonic disturbances decreases, and their occurrence becomes more irregular (Overland and Walter, 1983).

3.2 Wind.

The prevailing wind direction over Puget Sound during the spring season is south-southwesterly. At NAS Whidbey Island, at the east end of the Strait of Juan de Fuca, the prevailing direction is west. Average velocities range from 6 to 9 kt around the Sound. By mid- to late May, the prevailing wind shifts to a summer pattern. It is characterized by nearly calm conditions during night and morning hours, becoming 5 to 15 kt during the afternoon and early evening hours. In central and south Puget Sound, the prevailing direction remains southwesterly. In the extreme northern part of the Sound, the direction becomes northwesterly by early afternoon as a sea breeze effect is established. Easterly winds prevail in the Strait of Juan de Fuca early in the season, but shift to westerly as the sea breeze regime become established. Winds in the Strait frequently decrease to near calm conditions during night and early morning hours or, in some cases, shift to light easterlies.

Strong, gusty winds occur in advance of transient extratropical low pressure systems moving through the area early in the season, but become infrequent as the season progresses. By the end of May, such occurrences are uncommon.

3.3 Temperature.

Average spring temperatures range from 48°F (9°C) early in the season to 61°F (16°C) by late June. High temperatures range from 55°F (13°C) on Whidbey Island early in the season to 71°F (22°C) in Olympia during June (Federal Climate Complex, Asheville, 1995). Near the waters of Puget Sound, the average date of the last freezing temperature is near mid-April (Overland and Walter, 1983). The temperature distribution for the Puget Sound region is depicted in Figure A-5, Figure A-6, Figure A-7, and Figure A-8.

3.4 Precipitation.

Precipitation totals decrease markedly during the spring season. Average monthly totals are shown in Figure A-17. The effect of the rain shadow of the Olympic Mountains is still evident during the season.

Figure A-17. Average precipitation totals during the months of March through June for the sites listed.

Data extracted from Federal Climate Complex, Asheville (1995).

4.0 SUMMER WEATHER

4.1 Typical Weather Patterns.

Most of the summer weather over Puget Sound is influenced by marine air from the Pacific Ocean moving over the region via the Strait of Juan de Fuca (Overland and Walter, 1983). Although transient low pressure systems still move through the Puget Sound region, they do so only infrequently, and are relatively weak in comparison to the winter and early spring events. The high pressure influence leads to a relatively dry season with typically clear afternoons and relatively warm temperatures.

4.2 Wind.

With one exception, prevailing winds during summer are southwesterly or south-southwesterly 7 to 8 kt. The exception is during September, when the central Sound area’s prevailing wind is northerly. The prevailing winds at NAS Whidbey Island, at the east end of the Strait of Juan de Fuca, are primarily westerly at 5 to 7 kt. Strong winds are uncommon, although an occasional marine air intrusion through the Strait of Juan de Fuca (usually following a period of warm temperatures in the lowlands west of the Cascade Mountains) can easily bring winds of 20 kt or more to the Strait of Juan de Fuca, Whidbey Island, and Admiralty Inlet. When occurring, the winds may reach NAVSTA Everett through Saratoga Passage as northwesterly.

4.3 Temperature.

Summer temperatures in the Puget Sound region are moderate. Maximum temperatures seldom exceed 80°F (27°C) in the central and south Sound, but temperatures of 100°F (38°C) have been recorded in Seattle at Portage Bay and 104°F (40°C) was recorded at Olympia. The prevailing westerly winds over the relatively cool waters of the Strait of Juan de Fuca limit average maximum temperatures at NAS Whidbey Island to 64°F (18°C) to 67°F (19°C). The highest temperature recorded at NAS Whidbey Island is 93°F (34°C). The temperature distribution for the Puget Sound region is depicted in Figure A-5, Figure A-6, Figure A-7, and Figure A-8.

4.4 Precipitation.

Summer precipitation totals are the lowest of the year. As shown in Figure A-18, July is the driest month, with each of the four sites shown in the figure recording an average of less than one inch accumulation.

Figure A-18. Average precipitation totals for the months of June through September for the sites listed.

Data extracted from Federal Climate Complex, Asheville (1995).

5.0 AUTUMN WEATHER

5.1 Typical Weather Patterns.

The autumn season is a transition season for the Puget Sound region. A common characteristic of the early autumn period is the continuing influence of the Pacific high-pressure system depicted in Figure A-1d (Overland and Walter, 1983). The high-pressure ridge eventually breaks down as the season progresses, and the area shifts to prevailing southwesterly winds as the upper level flow strengthens. By mid- to late October, the storm systems depicted in Figures A-1a and A-1b start to prevail as the transient extratropical storm systems and fronts that are associated with winter weather become common.

5.2 Wind.

Prevailing winds during the autumn season reflect the typical wind flow through Puget Sound when southerly conditions exist. The south Sound has prevailing south-southwesterly winds of 8 to 9 kt. Central Sound, near SEATAC Airport, has prevailing southerly winds of 9 to 10 kt. At NAS Whidbey, at the east end of the Strait of Juan de Fuca, has a prevailing wind of southeasterly 10 to 12 kt. Strong wind events are common by the end of October as extratropical storm systems move through the area. Some of the strongest winds experienced in Puget Sound occur during the autumn season. One of the strongest storms of record occurred on October 12, 1962 (Columbus Day). Winds of 20 kt or greater are routinely experienced during November and December. Gale force (34-47 kt) winds are occasionally experienced, especially in the northern portions of Puget Sound where the funneling of southerly flow is the greatest between the Cascade and Olympic Mountain ranges.

5.3 Temperature.

Average temperatures decrease rapidly as the season progresses and winter approaches. The average date of the first freezing temperature in the lowlands near Puget Sound is near the end of October. By December, the average maximum temperature is near 45°F (7°C) and the average minimum has lowered to 33°F (1°C) in the south Sound and 36°F (2°C) at NAS Whidbey Island.

5.4 Precipitation.

Precipitation totals increase markedly during the autumn season. This is especially true in the more southern portions of Puget Sound where the rain shadow effect of the Olympic Mountains is at a minimum. By December, Olympia (in the extreme south Sound) receives roughly three times the average monthly precipitation total that is recorded at NAS Whidbey Island (in the rain shadow at the east end of the Strait of Juan de Fuca) (Figure A-19).

Figure A-19. Average precipitation totals for the months of September through December for the sites listed.

Federal Climate Complex, Asheville (1995).

6.0 EXTREME EVENTS IN PUGET SOUND

The Puget Sound region routinely experiences many strong wind episodes during the late autumn, winter, and early spring seasons. Gale force (34-47 kt) winds are common in the more exposed locations and promontories around the Sound. Storm force (48-63 kt) winds occur with regularity in the exposed areas along the west coast of Washington State but are only rarely observed in Puget Sound. An extremely strong pressure gradient associated with a transient extratropical low pressure system, usually of the type depicted in Figure A1-b, can bring storm force winds to Puget Sound. One such storm moved northward along the coast in December 1995, and brought sustained winds commonly exceeding 50 kt to the Puget Sound region. A similar occurrence occurred in October 1962, during the infamous “Columbus Day Storm.” Each of the two cited storms caused extensive wind-related damage to western Oregon and Washington.

Another uncommon, but extreme, event occurs when an intense cold front is forced southward through the Puget Sound region. Because of the topography of the region, most of the strongest wind effects are felt north of Puget Sound proper in the region between Bellingham and Whidbey Island. One such event occurred in December 1990, when a strong Arctic front moved through the Puget Sound region. The event caused winds of 70 kt (35 m s^-1) to be recorded on the northwest coast of Fidalgo Island (approximately 10 nmi north of NAS Whidbey Island. See Figure 1). A nearby island sustained tree damage that was consistent with wind speeds of 98-136 kt (49-68 m s^-1) (Mass, et al., 1995). Wind speeds decreased significantly south of Fidalgo Island. NAS Whidbey Island recorded a maximum gust of 51 kt (25 m s^-1).

6.1 Specific Examples of Severe Weather Events in the Puget Sound Region.

The following sections detail five separate events that had significant impact on the Puget Sound region. Each of the first four is identified by synoptic type as depicted in Figure A-1. The strongest wind and most severe weather data are provided for each event for selected locations around the Sound.

6.1.1 Strong Southerly Winds 12 and 13 October 1962 (Columbus Day Storm)

The Columbus Day Storm, occurring during 12 and 13 October 1962, caused widespread wind-related damage in Oregon and Washington. The synoptic situation is most closely related to Low Type 2 as shown in Figure A-1b. The primary low pressure center is located west of British Columbia in the southeastern Gulf of Alaska. Secondary low pressure centers form to the southwest of the main center and move northeastward toward Puget Sound. The winds had two peak periods in the Puget Sound region. The first strong winds were recorded primarily from 12/08Z to 12/11Z as a 974 mb low pressure center was located off the Washington coast, approximately 180 nmi west of the Olympic Peninsula. A second peak wind event occurred during the period 13/04Z to 13/08Z, when a 982 mb low pressure center was located approximately 180 nmi west of the southern Washington coast. A 36-hour chronology of the surface synoptic situation, in 12-hour increments, is shown in Figure A-20a, Figure A-20b, Figure A-20c, and Figure A-20d.

Figure A-20. Surface synoptic analyses, in 12-hour increments, for the 36-hour period

Figure A-20a 1200Z 11 October 1962

Figure A-20b 0000Z 12 October 1962

Figure A-20c 1200Z 12 October 1962

Figure A-20d 0000Z 13 October 1962

Table A-4. Observed winds and weather at selected locations around the Puget Sound region during the period 11-13 October 1962. The listed weather is the most severe reported, and did not necessarily coincide with the strongest winds at the reporting station. All listed stations report aviation hourly observations except for an automatic weather station on Smith Island, which reports three-hourly observations.

LOCATION

DATE/TIME

(YYMMDDHH)

MAXIMUM WINDS (KT)

MINIMUM

SEA LEVEL PRESSURE

WEATHER

BELLINGHAM

62101210Z

62101308Z

SSE 30G60

SSE 50G85

989.8 MB

978.9 MB

NONE REPORTED

RAIN

NAS WHIDBEY IS.

62101211Z

62101307Z

SSE 28G46

SSE 36G58

990.1 MB

978.6 MB

LIGHT RAIN

SMITH ISLAND

62101306Z

SSE 52G56

N/A

PAINE FIELD

62101208Z

62101306Z

SE 24G42

S 45G70

N/A

978.2E MB

NONE REPORTED

THUNDER SHOWERS

BOEING FIELD

62101304Z

SSE 38G57

979.2 MB

LIGHT RAIN

SEATAC AIRPORT

62101118Z

62101308Z

ESE 26G40

SSW 38G48

987.5 MB

978.7 MB

LIGHT RAIN

MCCHORD AFB

62101209Z

62101304Z

S 21G34

S 45G76

988.1 MB

977.6 MB

LIGHT RAIN SHOWERS

LIGHT RAIN

GRAY FIELD

62101208Z

62101305Z

S 20G40

SSE 30G45

987.8 MB

977.0 MB

LIGHT RAIN SHOWERS

LIGHT RAIN

OLYMPIA

62101209Z

62101304Z

SW 25G32

SW 45G60

976.3 MB

987.7 MB

LIGHT RAIN

RAIN

6.1.2 Strong Southerly Winds 16 and 17 November 1991.

Strong winds in the Puget Sound region occurred during 16 and 17 November 1991. The synoptic situation approximates Low Type 1, depicted in Figure A-1a. A strong, developing low pressure system moved eastward across the Gulf of Alaska toward the coast of southern British Columbia before recurving northward back into the Gulf of Alaska. The low established a strong southerly gradient over the Puget Sound region. Although not as strong as other events, sustained wind speeds approached gale velocities, and storm force gusts were recorded at two stations. A 36-hour chronology of the surface synoptic situation, in 12-hour increments, is shown in Figure A-21a, Figure A-21b, Figure A-21c, and Figure A-21d. The strongest winds and most severe weather associated with the storm are listed in Table A-4.

Figure A-21. Surface synoptic analyses, in 12-hour increments, for the 36-hour period

Figure A-21a 1200Z 15 November 1991

Figure A-21b 0000Z 16 November 1991

Figure A-21c 1200Z 16 November 1991

Figure A-21d 0000Z 17 November 1991

Table A-5. Observed winds and weather at selected locations around the Puget Sound region on 16 and 17 November 1991. The listed weather is the most severe reported, and did not necessarily coincide with the strongest winds at the reporting station. All listed stations report aviation hourly observations.

LOCATION	DATE/TIME (YYMMDDHH)	MAXIMUM WINDS (KT)	MINIMUM SEA LEVEL PRESSURE	WEATHER
BELLINGHAM	91111620Z	S 25G37	982.8 MB	LIGHT RAIN SHOWERS
NAS WHIDBEY IS.	91111615Z	SSE 29G52	999.2 MB	LIGHT RAIN
BOEING FIELD	91111707Z	S 22G39	N/A	LIGHT RAIN
SEATAC AIRPORT	91111707Z	S 20G27 PEAK WIND 29	988.4 MB	LIGHT RAIN SHOWERS
MCCHORD AFB	91111707Z	SSW 32G52	988.1 MB	LIGHT RAIN SHOWERS
GRAY FIELD	91111620Z 91111707Z	S 23G31 SSW 30G47 PEAK WIND 53	N/A 987.6 MB	LIGHT RAIN SHOWERS THUNDER SHOWERS
OLYMPIA	91111707Z	SW 26G32 PEAK WIND 41	988.8 MB	LIGHT RAIN

6.1.3 Strong Southerly Winds 12 and 13 December 1995.

A prolonged episode of strong winds affected the Puget Sound region on 12 and 13 December 1995. As shown in Figure A-22a, a large low pressure center was located in the northwest Gulf of Alaska. A developing low formed in the westerly flow south of the primary low’s center at 40°N. The low then moved northeastward toward southwestern British Columbia. This sequence of events placed the entire Pacific Northwest in strong southerly flow east of the low center. A Public Information Statement issued by the National Weather Service, Seattle, Washington listed extremely strong winds that were recorded at many locations. The list included: Sea Lion Caves off the central Oregon coast, which recorded 104 kt (120 mph) winds; a ship located on Puget Sound west of Seattle that reported 56-61 kt (65-70 mph) sustained winds with a gust to 78 kt (90 mph); and the city of Mukilteo (located just south of Naval Station, Everett) reported 52-61 kt (60-70 mph) sustained winds with a gust to 75 kt (86 mph). Several other locations in the Puget Sound area recorded winds between 48 kt (55 mph) and 61 kt (70 mph). A 36-hour chronology of the surface synoptic situation, in 12-hour increments, is shown in Figure A-22a, Figure A-22b, Figure A-22c, and Figure A-22d. The strongest winds and most severe weather associated with the storm at selected official reporting stations are listed in Table A-5. Sea level pressures reported by the observing stations were extremely low during this storm event.

Figure A-22. Surface synoptic analyses, in 12-hour increments, for the 36-hour period

Figure A-22a 1200Z 11 December 1995

Figure A-22b 0000Z 12 December 1995

Figure A-22c 1200Z 12 December 1995

Figure A-22d 0000Z 13 December 1995

Table A-6. Observed winds and weather at selected locations around the Puget Sound region on 12 and 13 December 1995. The listed weather is the most severe reported, and did not necessarily coincide with the strongest winds at the reporting station. All listed stations report aviation hourly observations except for Buoy WPOW1 at West Point, which reports three-hourly observations.

LOCATION	DATE/TIME (YYMMDDHH)	MAXIMUM WINDS (KT)	MINIMUM SEA LEVEL PRESSURE	WEATHER
BELLINGHAM	95121307Z	SSW 32G49 PEAK WIND 66	960.6 MB	RAIN
NAS WHIDBEY IS.	95121305Z	SSE 35G46 PEAK WIND 50	969.9 MB	LIGHT RAIN
BUOY WPOW1 (WEST POINT)	95121303Z	S 47G55 PEAK WIND 59	N/A	N/A
BOEING FIELD	95121304Z	SSE 35G40 PEAK WIND 41	N/A	LIGHT RAIN
SEATAC AIRPORT	95121304Z	SSW 36G47 PEAK WIND 52	970.2 MB	LIGHT RAIN SHOWERS
MCCHORD AFB	95121301Z	S 30G42	969.8 MB	LIGHT RAIN SHOWERS
GRAY FIELD	95121301Z	S 28G37 PEAK WIND 38	969.7 MB	LIGHT RAIN SHOWERS
OLYMPIA	95121223Z	SSE 29G50	968.9 MB	LIGHT RAIN

6.1.4 Strong Southerly Winds 12 and 13 February 1979.

A strong wind event occurred in February 1979 that resulted in a large section of the Hood Canal Floating Bridge (see Section 1.4) being destroyed by the force of the wind. The synoptic situation was similar to Low Type 2 as depicted in Figure A-1b. At 0000Z on 12 February a 996 mb low pressure center was located near 32°N 142°W, approximately 1,400 nmi southwest of Puget Sound. The semi-permanent Gulf of Alaska Low was a relatively weak 1004 mb and located at 52.5°N 135°W. By 1200Z on 12 February the low southwest of Puget Sound had deepened to 985 mb and moved northeastward approximately 650 nmi. During the next 12 hours, the low pressure center had deepened to 978 mb and moved an additional 360 nmi closer to Puget Sound. By 1200Z on 13 February, the low had a center pressure of 981 mb, and was located over Vancouver Island. A 36-hour chronology of the surface synoptic situation, in 12-hour increments, is shown in Figure A-23a, Figure A-23b, Figure A-23c, and Figure A-23d.

Figure A-23. Surface synoptic analyses, in 12-hour increments, for the 36-hour period

Figure A-23a 0000Z 12 February 1979

Figure A-23b 1200z 12 February 1979

Figure A-23c 0000Z 13 February 1979

Figure A-23d 1200Z 13 February 1979

Winds in the Puget Sound during the storm’s passage were strongest in the area of the Hood Canal. Reed (1980) did a detailed analysis of the event, and concluded that a mesoscale low pressure system (vortex) formed in the lee of the Olympic Mountains as the low pressure system moved ashore on Vancouver Island. The formation of the lee side low pressure caused an extremely strong pressure gradient (5 mb difference over a distance of less than 10 nmi) over Hood Canal. According to Reed (1980), winds measured at the Hood Canal Bridge reached 50 mph at 120930Z, and 80 mph by 1121400Z. The bridge failed at approximately 131500Z. By 131600Z the entire 3,200 ft west section of the bridge had been destroyed and/or sunk.

Table A-6 lists the strongest winds and most severe weather associated with the storm at selected official reporting stations.

Table A-7. Observed winds and weather at selected locations around the Puget Sound region on 13 February 1979. The listed weather is the most severe reported, and did not necessarily coincide with the strongest winds at the reporting station. All listed stations report aviation hourly observations, except for West Point Light House which reports three-hourly observations.

LOCATION	DATE/TIME (YYMMDDHH)	MAXIMUM WINDS (KT)	MINIMUM SEA LEVEL PRESSURE	WEATHER
BELLINGHAM	79021313Z	SSE 33G62 PEAK WIND 65	987.1 MB	LIGHT RAIN SHOWERS
NAS WHIDBEY IS.	79021312Z	S 40G48 PEAK WIND 58	987.5 MB	LIGHT RAIN SHOWERS
WEST POINT LIGHT HOUSE	79021312Z	S 40G47	N/A	RAIN (SEAS 3-4 FT)
BOEING FIELD	79021315Z	S 22G32	N/A	LIGHT RAIN SHOWERS
SEATAC AIRPORT	79021310Z	S 32G52	991.7 MB	LIGHT RAIN SHOWERS
BREMERTON AIRPORT	79021317Z	SSW 22G38	N/A	LIGHT RAIN WITH FOG
MCCHORD AFB	79021309Z	S28G46	992.5 MB	LIGHT RAIN SHOWERS
GRAY FIELD	79021308Z	S 26G35 PEAK WIND 48	992.2 MB	LIGHT RAIN
OLYMPIA	79021311Z	S25G34	992.3 MB	LIGHT RAIN SHOWERS

6.1.5 Strong Cold Frontal Passage 27 and 28 December 1990.

An unusually strong cold front passed through the Puget Sound region on 27 and 28 December 1990. As shown in Figure A-24a, Figure A-24b, Figure A-24c, and Figure A-24d, a relatively deep low pressure system moved southeastward from Alaska to a position over northern Idaho. An intense, cold high pressure cell moved southeastward behind the low, creating a strong northeasterly pressure gradient. Cold air moving southward through the Fraser River Valley in southern British Columbia spilled into the waters north of Puget Sound. Wind velocities reached 55 kt at Bellingham, with lesser speeds recorded at other locations. The force of the wind was sufficiently strong to cause catastrophic loss of conifer timber on several islands southwest of Bellingham. Deception Pass Park, a state park located on the north end of Whidbey Island, suffered a loss of over 3,000 trees.

Figure A-24. Surface synoptic analyses, in 12-hour increments, for the 36-hour period

Figure A-24a 1200Z 26 December 1990

Figure A-24b 0000Z 27 December 1990

Figure A-24c 1200Z 27 December 1990

Figure A-24d 0000Z 28 December 1990

Table A-8 lists the strongest winds associated with the front and times of frontal passage at selected official reporting stations.

Table A-8. Observed winds and weather at selected locations around the Puget Sound region on 28 December 1990. All listed stations report aviation hourly observations.

LOCATION	DATE/TIME (YYMMDDHH)	MAXIMUM WINDS (KT)	WEATHER	TIME OF APPARENT FRONTAL PASSAGE*
BELLINGHAM	90122809Z	NNE 35G55	LIGHT SNOW	90122803Z
NAS WHIDBEY IS.	90122815Z	N 30G46	LIGHT SNOW	90122804Z
BOEING FIELD	90122812Z	NNW 25G35	LIGHT SNOW SHOWERS	90122810Z
SEATAC AIRPORT	90122817Z	N 28G37	LIGHT SNOW	90122810Z
BREMERTON AIRPORT	90122814Z	N 28G40	N/A	N/A
MCCHORD AFB	90122819Z	NNE 24G38	LIGHT SNOW	90122811Z
GRAY FIELD	90122820Z	N 26G47	HEAVY SNOW	90122811Z
OLYMPIA	90122823Z	ENE 18G26 PEAK WIND 27	LIGHT SNOW	90122812Z

Time of frontal passage estimated from observation records.

APPENDIX B

SOURCES OF WEATHER FORECASTS AND WARNINGS

1.0 GENERAL

Forecasts and warnings for the Puget Sound region are issued by Naval Pacific Meteorology and Oceanography Detachment (NPMOD) Whidbey Island and the National Weather Service Forecast Office (NWSFO) at Sand Point in Seattle. Weather forecasts and warning information originating with NWSFO Sand Point are available from a variety of sources in the Puget Sound area, including very high frequency (VHF) weather radio broadcasts, by telephone to the Seattle Times InfoLine, and broadcast media (radio/television). Routine dissemination of the NPMOF Whidbey Island forecasts and warnings is more restricted. Methods of dissemination include AUTODIN distribution to AIG 7740, and by telephone at their NAS Whidbey Island offices.

2.0 SPECIFIC SOURCES OF WEATHER FORECASTS AND WARNINGS

2.1 VHF Weather Radio Broadcasts.

VHF Weather broadcasts are an easy-to-use source of up-to-date weather data. At the time of this writing, four radio transmitters are operated by the National Weather Service (NWS) and two are operated by the Atmospheric Environment Service (AES) of Canada for the waters of western Washington and southern British Columbia. Each transmitter has a targeted area of reception. The VHF broadcasts are described in the following paragraphs and figures. Some of the following data has been extracted from Lilly (1983), with updated information provided by the National Weather Service Office at Sand Point in Seattle.

2.1.1 VHF Weather Radio KHB-60.

Frequency: 162.55 MHz (“Weather 1” or “WX1” on some VHF radios)

Transmitter location: Gold Mountain near Bremerton, WA.

Transmission Contents: Forecasts and weather observations are broadcast 24 hours a day.

Contents of the transmission are:

1. Station identification.

2. Marine forecasts:

a. Puget Sound and Hood Canal

b. Camano Island to Point Roberts

c. Strait of Juan de Fuca and Admiralty Inlet

d. Cape Flattery to mouth of Columbia River out to 60 nmi

3. Weather observations for the stations identified on Figure B-1.

4. Weather summary, Seattle forecast, mountain forecast.

5. Western Washington forecast.

6. Eastern Washington forecast.

7. Six to 10 day outlook.

8. Seattle forecast.

9. Travelers forecast, river reports, mountain pass reports, avalanche statements, and other pertinent weather statements.

The weather observation points for KHB-60 shown in Figure B-1 are located at sites of varying distance from the water. Those sites on or near the water would be more representative of conditions of interest to mariners than would those farther from the water, or at significant elevations above the waters of Puget Sound. Not all stations take observations around the clock, so some reports are omitted from 5:00 pm to 6:00 am. Some of the sites are being automated, so the regularity of reports from some sites will improve with time. Some observations may be omitted from the broadcasts due to equipment or communication failures.

Figure B-1. Weather observation sites included in KHB-60 VHF NOAA Weather Radio broadcasts.

The approximate area of reception is shown by the shaded area enclosed by the dark, heavy line.

It should be noted that the broadcast frequency of KHB-60 is the same as Canadian Weather Radio Station XLA-852, described in the following Section 2.1.6. Because the two stations use the same broadcast frequency, there is an overlap in the reception area north of central Whidbey Island. Reception is often unintelligible in the area of overlap. To correct the problem, a new NOAA Weather Radio station is planned. The broadcast is scheduled to utilize VHF frequency 162.525 MHz, and be broadcast from Miller Peak, southwest of Port Angeles, WA. The new station, call letters as yet unknown, is scheduled to be operating during the last week of September 1996.

The broadcast is continuous, 24-hours a day. Although observations are taken hourly at many sites, the observations are only updated every three hours on the broadcast (at 1:00, 4:00, 7:00 and 10:00 am and pm, Pacific Standard Time (PST) during the winter, and one hour later during the summer when Pacific Daylight Time (PDT) is in effect). Marine forecasts are updated at 2:30 and 8:30 am and pm, PST in the winter, and 3:30 and 9:30 am and pm PDT during the summer.

2.1.2 VHF Weather Radio KIH-36.

Frequency: 162.55 MHz (“Weather 1” or “WX1” on some VHF radios)

Transmitter location: Bahokus Peak near Neah Bay, WA.

Transmission Contents: Forecasts and weather observations are broadcast 24 hours a day.

Contents of the transmission are:

1. Station identification.

2. Coastal zone forecast, coastal zone summary.

3. Marine forecasts:

a. Offshore (60-250 nmi off Washington coast)

b. Coastal (Washington coast out to 60 nmi)

c. Strait of Juan de Fuca

d. Inland waters

e. Canadian forecasts for Strait of Juan de Fuca and west coast of Vancouver Island

f. Grays Harbor Bar forecast (updated at 2:00 pm PST and 3:00 pm PDT)

4. Weather observations for the stations identified on Figure B-2.

5. Coastal forecast (for land areas along Washington coast).

6. Northwest interior forecast for Washington.

7. Mountain forecast.

8. Six to 10 day outlook.

9. Special features (if any), such as special discussion of holiday weather.

The weather observation points for KIH-36 shown in Figure B-2 are located at sites of varying distance from the water. Those sites on or near the water would be more representative of conditions of interest to mariners than would those farther from the water, or at significant elevations above the waters of Puget Sound. Not all stations take observations around the clock, so some reports are omitted from 5:00 pm to 6:00 am. Some of the sites are being automated, so the regularity of reports from some sites will improve with time. Some observations may be omitted from the broadcasts due to equipment failures.

Figure B-2. Weather observation sites included in KIH-36 VHF NOAA Weather Radio broadcasts.

The approximate area of reception is shown by the shaded area enclosed by the dark, heavy line.

The broadcast is continuous, 24-hours a day. Although observations are taken hourly at many sites, the observations are only updated every three hours on the broadcast (at 1:00, 4:00, 7:00 and 10:00 am and pm, Pacific Standard Time (PST) during the winter, one hour later during the summer when Pacific Daylight Time (PDT) is in effect). Marine forecasts are updated at 2:30 and 8:30 am and pm, PST in the winter, and 3:30 and 9:30 am and pm PDT during the summer.

2.1.3 VHF Weather Radio KEC-91.

Frequency: 162.40 MHz (“Weather 2” or “WX2” on some VHF radios)

Transmitter location: Naselle Ridge, about 15 nmi northeast of Ilwaco, WA.

Transmission Contents: Forecasts and weather observations are broadcast 24 hours a day.

Contents of the transmission are:

1. Station identification.

2. State forecasts for western Washington and Oregon, and forecast for Astoria and vicinity.

3. Marine forecasts:

a. Coastal forecast for Washington (updated at 2:30 and 8:30 am and pm PST and 3:30 and 9:30 am and pm, PDT)

b. Grays Harbor Bar forecast (updated 2:00 pm, PST and 3:00 pm PDT)

c. Columbia River Bar forecast (updated 10:00 am and pm, PST and PDT)

d. Coastal forecast for Oregon (updated at 2:30 and 8:30 am and pm PST and 3:30 and 9:30 am and pm, PDT

e. Offshore forecast (60 to 250 nmi offshore) for area from Cape Flattery, WA to Cape St. George, CA (updated at 2:30 and 8:30 am and pm PST and 3:30 and 9:30 am and pm, PDT)

4. Weather observations. (Astoria and Columbia River buoy observations are updated hourly. The remainder are only available from either 4:00 am or 7:00 am PST until 7:00 pm PST and are updated every three hours). See Figure B-3.

5. Oregon coastal discussion (broadcast from 4:00 am to 6:00 am and 6:00 pm to 9:30 pm PST and PDT). This is a specially tailored weather discussion for mariners. A 48-hour outlook for marine weather is included.

6. Ocean Thermal boundary bulletin (broadcast on a seasonal basis from April through October from 4:00 am to 6:00 am and 6:00 pm to 8:00 pm PDT). The bulletin contains information about the surface temperature structure of the ocean off Oregon and Washington. The information is updated once a week on Thursday beginning with the 6:00 pm broadcast.

Figure B-3. Weather observation sites included in KEC-91 VHF NOAA Weather Radio broadcasts.

The approximate area of reception is shown by the shaded area enclosed by the dark, heavy line.

2.1.4 VHF Weather Radio WXM-62.

Frequency: 162.475 MHz (“Weather 3” or “WX3” on some VHF radios)

Transmitter location: Boistfort Peak about 40 nmi south-southwest of Olympia

Transmission Contents: Forecasts and weather observations are broadcast 24 hours a day and

repeated every five to seven minutes. Transmission contents are routinely

revised every one to three hours or more frequently if needed. Contents of

the transmission are:

1. Station identification.

2. Local forecasts:

a. Southwest interior

b. Washington coast

c. Cascades and Olympia

3. Three to five day extended outlook.

4. Six to 10 day outlook.

5. Marine forecasts:

a. Cape Flattery to mouth of Columbia River out to 60 nmi

b. Puget Sound and Hood Canal

c. Grays Harbor Bar

6. Weather reports for the stations shown in Figure B-4.

7. Washington weather discussion.

Other products are broadcast at various times during the day and the

program content is adjusted seasonally to accommodate the changing

needs of residents. This includes:

1. Climate data from Olympia Airport.

2. Mt. Rainier recreation forecast.

3. Winter weather conditions over mountain passes.

Warnings, watches and advisories for conditions such as tornadoes, severe

thunderstorms, high winds, heavy snow or avalanches are broadcast as

necessary and may pre-empt regular programming.

Figure B-4. WXM-62 VHF NOAA Weather Radio broadcast. area. The approximate area of

reception is shown by the shaded area enclosed by the dark, heavy line.

2.1.5 VHF Weather Radio CFA-240.

Frequency: 162.40 MHz (“Weather 2” or “WX2” on some VHF radios)

Transmitter location: Mount Taum on Saltspring Island near Victoria, B.C.

Transmission Contents:

1. Weather synopsis for British Columbia.

2. Area forecasts:

a. Greater Vancouver

b. Lower Mainland

c. East Vancouver Island and Sunshine Coast

d. North and West Vancouver Island

e. Greater Victoria

3. Western Washington public forecast.

4. Cross-Canada weather picture (carried approximately 7:00 am to 11:30 pm).

5. Marine Weather synopsis for British Columbia.

6. Marine Forecasts:

a. Georgia Strait (updated at 5:00 am, 11:00 am, and 7:00 pm PST)

b. Strait of Juan de Fuca (updated at 5:00 am, 11:00 am, and 7:00 pm PST)

c. Northern inland waters of Washington state.

7. Latest lighthouse reports for stations shown in Figure B-5. Reports are included from approximately 6:00 am to 11:30 pm.

8. Mountain weather synopsis (winter months) with area forecasts for Vancouver Island mountains and South Coast mountains.

Figure B-5. Weather observation sites included in CFA-240 Canadian AES VHF Weather Radio broadcasts.

The approximate area of reception is shown by the shaded area enclosed by the heavy line.

2.1.6 VHF Weather Radio XLA-852.

Frequency: 162.55 MHz (“Weather 1” or “WX1” on some VHF radios)

Transmitter location: Aldergrove, B.C. (near Abbotsford, B.C.)

Transmission Contents: Taped weather messages are repeated every four to seven minutes, and are

routinely revised every one to three hours, or more frequently if needed.

The broadcast includes:

1. Regional weather discussion.

2. Local forecasts and three to five day extended forecasts for:

a. Lower Fraser River Valley

b. Northwest Interior of Washington

3. Agricultural forecast for the Lower Fraser River Valley.

4. Selected regional weather conditions updated each hour.

5. Environmental information.

Warnings, watches and advisories for conditions such as severe thunderstorms, high winds, U.S. floods, heavy snow or avalanches are broadcast as necessary and may preempt regular programming.

The broadcast can be heard across the Lower Fraser River Valley and Lower Nooksack River Basin north and east of Bellingham, WA, and south to central Whidbey Island. Programming is in cooperation with the National Weather Service Office in Seattle, Washington, making it the only international weather radio station in the world.

It should be noted that the broadcast frequency of XLA-852 is the same as U.S. NOAA Weather Radio Station KHB-60, described in Section 2.1.1. Because the two stations use the same broadcast frequency, there is an overlap in the reception area north of central Whidbey Island. As a result, reception is often unintelligible in the area of overlap. To correct the problem, a new U.S. NOAA Weather Radio station is planned. The broadcast is scheduled to utilize VHF frequency 162.525 MHz, and be broadcast from Miller Peak, southwest of Port Angeles, WA. The new station is scheduled to be operating during the last week of September 1996.

2.2 Telephone Numbers for Obtaining Weather Forecast/Warning Information

2.2.1 Naval Pacific Meteorology and Oceanography Command Detachment, Whidbey Island.

(360) 257-2675 “Dial-a-Forecast” continuously updated, recorded Whidbey Island area 24-hour forecast.

(360) 257-2244 Forecast Duty Officer.

2.2.2 Seattle.

The Seattle Times newspaper maintains a telephone information news service called the “InfoLine,” through which weather forecasts and pertinent warning information are available. In addition to weather data, the service also provides information on a multitude of subjects, including ferry schedules and tide information as well as several other areas of interest.

InfoLine is accessed by dialing 464-2000 on a touch tone phone. It is a free call from the Seattle calling area. When connected to InfoLine, the user must then dial a four-digit number to obtain National Weather Service forecast and/or warning information. The pertinent numbers are as follows:

General

How to use InfoLine................................................................. 9930

Main Directory......................................................................... 1000

Non-Marine Forecasts and Warnings

Southwest Washington Interior.................................................. 9901

Seattle, Everett, Tacoma and Vicinity........................................ 9902

Washington State Weather Summary......................................... 9903

Washington Cascades and Olympic Mountains..........................9904

Western Washington Extended Forecast....................................9907

Eastern Washington and Extended Forecast...............................9908

Mt. Rainier Recreational Forecast............................................. 9915

Mountain Pass Report.............................................................. 9917

Marine Forecasts and Warnings

Cape Flattery, Mouth of the Columbia River and Coastal Waters

out to 60 miles..............................................................9909

Puget Sound and Hood Canal Marine Forecast.........................9910

Strait of Juan de Fuca and Admiralty Inlet..................................9911

Camano Island to Point Roberts Marine Forecast......................9913

Coastal Zone Forecast..............................................................9914

Surf Report.............................................................................. 9919

Specific weather data for over 100 cities in the United States and countries around the world can also be obtained via InfoLine. The preceding Main Directory number should be dialed to obtain the correct four-digit extension number for the location desired.

2.3 Broadcast Media (Radio/Television).

The following commercial radio and television stations routinely broadcast weather forecasts for the Puget Sound area during their regular programming. Forecasts are provided periodically during normal operating hours, with updated forecasts and/or high wind warnings broadcast as necessary. Other television and radio stations in the area may provide similar information.

KOMO Television, Channel 4 KOMO Radio, 1000 KHz am

KING Television, Channel 5 KIRO Radio, 710 KHz am

KIRO Television, Channel 7

KSTW Television, Channel 11

2.4 Global Maritime Distress and Safety System.

A new system of distributing maritime safety information to all ships over 300 gross tons around the world is scheduled to become fully operational on 1 February 1999. The system is called the Global Maritime Distress and Safety System (GMDSS) (National Weather Service, undated). Although the target date is not likely to be met by all ships from all countries, the system is progressing toward full implementation. The system requires special equipment and training and, at the time of this writing, many ships have not been fitted with the equipment, many deck officers have not been trained, and many national administrations have done little to implement the shoreside infrastructure.

GMDSS has the following features: transmission and receipt of safety information, including meteorological warnings and forecasts, navigational warnings and other urgent safety related information; distress alerting—ship-to-shore, shore-to-ship, and ship-to-ship; search and rescue coordination; on-scene and bridge-to-bridge communications; and locating signals. GMDSS will operate in parallel with the present system for delivery of maritime safety information until 1 February 1999. After that time, GMDSS will become the primary international means for disseminating maritime safety information to mariners.

Science Applications International Corporation

Meteorological Applications Development Branch Marine Meteorology Division

TABLE OF CONTENTS

ACKNOWLEDGEMENTS

SUMMARY

REFERENCES

APPENDIX A

APPENDIX B