Advancing the Prediction of Rapid Intensification of Typhoon

Some typhoons undergo a rapid intensification process, which causes them to become stronger typhoons. Rapid Intensification (RI) is defined as the increase in maximum sustained winds to 30 kt (15 m/s) or more within a 24-hour period (Kaplan and DeMaria, 2003). Typhoons that have undergone RI mainly strengthen into strong LMIs, which can cause significant damage in a relatively short period of time. The recent increase in the number of cases of RI of typhoons has highlighted the importance of advanced forecasting. However, achieving accuracy in these forecasts remains a significant challenge. In general, the intensity of typhoons is highly dependent on tehrmal conditions, such as ocean temperatures. However, the process of rapid intensity development is complex and influenced by dynamic factors, such as upper-level divergence and vertical wind shear. In this study, we developed a guidance for predicting the probability of rapid intensity development in a typhoon using environmental prediction factors at the time of its occurrence. The purpose of this study is to support KMA's typhoon forecasting. A logistic regression method was used to construct a classification prediction model for typhoons (56 cases of RI, 170 cases of non-RI) that occured from Junt to November between 2011 and 2020 (over the past 10 years). The predictor variables included upper-level divergence, relative humidity, sea surface temperature, tropical cyclone heat potential (TCHP), thermodynamic net energy gain rate (NGR) (Lee et al., 2019), and wind radius. To evaluate the accuracy of regression predictions for typhoons that occured between June and November 2021-2022 within a 24-hour period, 6 cases of RI and 34 cases of non-RI were analyzed. The results indicated that the prediction accuracy (Acc) was approximately 93%. The hit rate (CSI) was approximately 0.43, and the false alarm rate (FAR) was approximately 6%. The developed prediction model has been utilized as a typhoon forecasting system by the NTC/KMA through real-time operation since 2023.