1998 Annual Tropical Cyclone Report
Abstract
The 1998 tropical cyclone forecasting season was one of the most challenging in the 39-year history of the Joint Typhoon Warning Center (JTWC) due to the nature of the forecast season and the move of JTWC from Guam to Hawaii. In terms of forecast difficulty, the 1998 Western Pacific (WESTPAC) season was one of the toughest in the past two decades based upon the performance of the Climatology and Persistence (CLIPER) model (which provides us a baseline against which to measure our forecast skill). We also noted a number of anomalies in WESTPAC, many of which could be traced to the well-documented La Nina event that was on-going throughout the season. First, we had a very late start to the season. Our initial named storm, Tropical Storm Nichole, did not occur until 7 July. This was the latest occurrence for a named storm since JTWC has been keeping records (1959). We also had fewer tropical cyclones (tropical depressions and storms, typhoons and super-typhoons) than average with 27 in 1998 versus an average of approximately 31. The tropical cyclones that occurred also tended to be less intense than average. In 1998, we had 9 Tropical Depressions (TD), 9 Tropical Storms (TS), and 9 Typhoons (TY). We would expect an average (again, approximate) of 4 TD, 10 TS, and 18 TY. We definitely experienced a much higher percentage of TDs than usual and a significantly lower percentage of typhoons. The genesis areas for the storms was also substantially displaced to the west with a higher percentage of the storms forming in the South China Sea and fewer east of Guam than we normally expect. This point is amplified later in the report.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA381675
Entities
People
- W. T. Aldinger
- Wendell Stapler