Evaluation and Error Analysis of Official Tropical Cyclone Intensity Forecasts during 2005–2018 for the Western North Pacific

This study systematically evaluates the accuracy, trends, and error sources for western North Pacific tropical cyclone intensity forecasts between 2005 and 2018. The study uses homogeneous samples from tropical cyclone (TC) intensity official forecasts issued by the China Meteorological Administration (CMA), Joint Typhoon Warning Center (JTWC), and Regional Specialized Meteorological Center Tokyo-Typhoon Center (RSMC-Tokyo). The TC intensity forecast accuracy performances are as follows: 24–48 h, JTWC > RSMC-Tokyo > CMA; 72 h, JTWC > CMA > RSMC-Tokyo; and 96–120 h, JTWC > CMA. Improvements in TC intensity forecasting are marginal but steady for all three centers. The 24–72 h improvement rate is approximately 1–2 % yr−1. The improvement rates are statistically significant at the 95 % level for almost half of the verification times from 0–120 h. The three centers tend to overestimate weak TCs over the northern South China Sea, but strong TCs are sometimes underestimated over the area east of the Philippines. The three centers generally have higher skill scores associated with forecasting of rapid weakening (RW) events than rapid intensification (RI) events. Overall, the three centers are not skillful in forecasting RI events more than three days in advance. Fortunately, RW events could be forecasted five days in advance with an accuracy order of CMA > RSMC-Tokyo > JTWC.