Modified Waldvogel Method Based on Identification of Hail Parameter Characteristics Using Dual Radar in the Central Part of Java

Hail is a severe weather event that can cause both material damage and loss of life. It can be identified through weather radar using the Waldvogel method. In Indonesia, research on this method is mainly concentrated in the western and eastern parts of Java. However, the latest data in the last five years shows an increasing trend in the occurrences of hail in central part of Java. Hence, there is a need for research on the Waldvogel method in this area. This study employs the ZHAIL product within the Rainbow 5 weather radar system. Given central Java's tropical climate, adjustments to the method are necessary. These modifications stem from analyzing key hail parameters, including maximum reflectivity and elevation, drawn from two radar data sources, as well as freezing levels from ECMWF model data. Analyzing 18 hail cases from 2019 to 2023 yields two criteria for modifying probability of hail (POH). The modified POH and Waldvogel POH are then cross-verified using contingency tables to determine metrics like probability of detection (POD), critical success index (CSI), and false alarm rate (FAR). Verification occurs within radar scanning limitations. For C-Band radar, optimal hail detection criteria are POH 1 within 0–60 km, POH 2 within 60–100 km, and the initial POH within 100–150 km. Meanwhile, X-Band radar best criteria is POH 2 within 0–60 km.