Forecasting Tropical Cyclones in the Western North Pacific Basin Using the NCEP Operational HWRF Model: Model Upgrades and Evaluation of Real-Time Performance in 2013

Abstract

his study presents evaluation of real-time performance of the National Centers for Environmental Prediction (NCEP) operational Hurricane Weather Research and Forecast (HWRF) modeling system upgraded and implemented in 2013 in the western North Pacific basin (WPAC). Retrospective experiments with the 2013 version of the HWRF Model upgrades for 2012 WPAC tropical cyclones (TCs) show significant forecast improvement compared to the real-time forecasts from the 2012 version of HWRF. Despite a larger number of strong storms in the WPAC during 2013, real-time forecasts from the 2013 HWRF (H213) showed an overall reduction in intensity forecast errors, mostly at the 4?5-day lead times. Verification of the H213?s skill against the climate persistence forecasts shows that although part of such improvements in 2013 is related to the different seasonal characteristics between the years 2012 and 2013, the new model upgrades implemented in 2013 could provide some further improvement that the 2012 version of HWRF could not achieve. Further examination of rapid intensification (RI) events demonstrates noticeable skill of H213 with the probability of detection (POD) index of 0.22 in 2013 compared to 0.09 in 2012, suggesting that H213 starts to show skill in predicting RI events in the WPAC.