Introduction

The U.S. Joint Typhoon Warning Center (JTWC) and the National Hurricane Center (NHC) use a variety of Numerical Weather Prediction (NWP) products and objective techniques for guidance in the tropical cyclone (TC) warning process. Multiple techniques are required, because each technique has particular strengths and weaknesses which vary by basin, numerical model initialization, time of year, synoptic situation and forecast period (JTWC, 1991). Forecasters at sea use global and regional model output on a daily basis and may see reference to objective guidance in TC warnings and prognostic discussions. This chapter provides a brief overview of modeling terminology and objective guidance. Background information on numerical modeling and definitions are given in Appendix A. Appendix B provides brief comparison tables for 1993 global numerical weather prediction systems at the European Centre for Medium-range Weather Forecasts (ECMWF), U.S. Fleet Numerical Meteorology and Oceanography Center (FNMOC), U.S. National Meteorological Center (NMC), and Japan Meteorology Agency (JMA). Appendix C has a general review of JTWC and NHC TC motion forecast aids.

Chapter 5