Evaluation of JTWC (Joint Typhoon Warning Center) Tropical Cyclone Objective Forecast Aids (1978-1985)

Abstract : The Joint Typhoon Warning Center (JTWC) official and objective aid forecasts for the Western North Pacific tropical cyclones during 1978-85 are evaluated. Forecast accuracy and consistency are judged on such error measures as forecast error, cross-track error, along-track error, track error, speed error and timing error, with respect to the best track of the tropical cyclone. Data also are stratified by the storm's intensity, type of path, and season, for further detailed comparisons. Considering all data groups, HPAC and OTCM emerged as the best and most consistent aids for the entire data period. Other aids, however, can surpass these two aids in specific synoptic situations. When tropical cyclones are in tropical storm stage, JTWC forecasts are most reliable. Two new aids introduced to JTWC in 1985 were among the best aids of that year.