Evaluation of Western North Pacific Tropical Cyclone Objective Forecast Aids

The Joint Typhoon Warning Center's (JTWC) official and objective aid forecasts for the western North Pacific tropical cyclones during 1978–85 are evaluated. Forecast accuracy is measured by the forecast error, cross-track error and along-track error with respect to the best track of the tropical cyclone. In addition, data are stratified by the storm's intensity for further detailed comparisons. Considering all stratifications, two aids emerged as best for the entire data period: the Half Persistence and Climatology (HPAC) and the One-way interactive Tropical Cyclone Model (OTCM). The HPAC is superior to OTCM for the tropical storm forecasts, but OTCM is superior for the typhoon and super-typhoon forecasts.