Real-Time Forecasts of Typhoon Rapid Intensification in the North Western Pacific Basin with the NCEP Operational HWRF model

Presentation Type: 
Vijay Tallapragada (NOAA/NCEP Environmental Modeling Center)

This study presents the real-time performance of the United States (US) National Centers

for Environmental Prediction (NCEP) operational Hurricane Weather Research and Forecast

(HWRF) model in predicting track, intensity, intensity change, and specifically the rapid

intensification (RI) of typhoons in the North Western Pacific (WPAC) basin in 2013 and 2014.

Since its initial implementation in 2012, HWRF model has shown superior tropical cyclone

track and intensity forecast skills compared to all other models operating in the WPAC basin,

and has become one of the consensus models used by various forecasting agencies in that region

including the US Navy’s Joint Typhoon Warning Center (JTWC). One of the striking features

of performance of the HWRF model in the WPAC basin is it’s ability to capture RI events more

accurately. Examination of all RI cases during 2013 shows that the HWRF model captures a

consistent vortex structure at the onset of all RI events consistent with previous idealized studies

using the HWRF model. However, the model has issues with predicting RI when the storms are

initialized with intensity greater than hurricane strength. Further verification of the probability of

detection (POD) and the false alarm rate (FAR) of RI forecasts in 2013 and 2014 shows that the

HWRF model outperforms all other models used by JTWC, possessing highest POD and lowest

FAR. Examination of the intensity change forecasts at different forecast lead times also confirms

that the HWRF model possesses superior performance, particularly at the 72-h lead time with

the POD index ~0.91 and the FAR index ~0.33. Such unique performance of the HWRF model

demonstrates its role in helping operational agencies to improve their official intensity (and RI)

forecasts for tropical cyclones in the WPAC basin.

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