Benchmarking and Verification of Rapid Intensification/Weakening of Tropical Cyclone Forecasts by HWRF Model

The National Hurricane Center's forecast verification shows large improvement in tropical cyclone (TC) track forecasts over the last decade. However, intensity forecasts remain a challenge. While some improvements in tropical cyclone (TC) intensity forecasting have been demonstrated, predicting large changes in TC intensity remains very problematic. This is particularly true for identifying episodes of rapid intensification (RI), which remains the highest operational forecasting priority of the National Hurricane Center (NHC). The difficulty of predicting RI is due in large part to the multi-scale nature of the problem with environmental, oceanic, and inner-core processes all likely playing important roles in determining if and when a TC will undergo RI. Rapid weakening (RW) is also a difficult and important forecasting challenge. The inability of models to forecast these large changes leads to huge intensity errors and contributes to the problem of intensity forecasting. This study establishes benchmarks for model performance for large changes in intensity, addressing both RI and RW. Additional analyses are included to document the characteristics of the forecasting errors. The primary focus is on the HWRF model, though other operational models are compared and contrasted. The methodology adopted for this study will be part of the Model Evaluation Tools for Tropical Cyclones (MET-TC) package. The MET-TC is a community software widely used for model evaluations. This verification methodology can be used for other applications like measuring solar ramp rates.