Analysis of a Hail Process in Foshan, Guangdong Province Using an Advanced Phased-Array Radar System and Development of a New Early Warning Index

Dual-Doppler radar detection and wind-field retrieval techniques are crucial for capturing small-scale structures within convective systems. The spatiotemporal resolution of radar data is a key factor influencing the accuracy of wind-field observations. Recently, an advanced X-band phased-array weather radar system was deployed in Foshan, Guangdong Province, China, comprising a central collaborative control unit and multiple networked phased-array radar front-ends. These radar front-ends work together to scan a common area, achieving a maximum data time difference of 5 s and a volume scan interval of 30 s, thereby providing three-dimensional wind-field data with higher spatiotemporal resolution and greater accuracy than achieved using traditional methods. This study utilized the X-band phased-array weather radar system to analyze the development of a substantial hailstorm that occurred over Foshan on 26 March 2022. Analysis indicated that hail cloud activity intensified considerably after 1442 local time, with the maximum reflectivity factor exceeding 60 dBZ above the altitude of the −20°C level, and reflectivity continued to increase over the subsequent 12 min. More precise information on the flow-field structure of the storm was obtained by examining the X-band radar data. The temporal and vertical variations in the maximum reflectivity factor, updraft velocity, vertical wind shear, and horizontal wind speed within a hailstorm cloud were scrutinized. The results show that the altitude, intensity, and range of the main updraft area increased as the storm core ascended. Concurrently, the vertical wind shear at mid‒lower levels of the storm became more pronounced as the altitude of the strong radar echo center increased prior to the peak of the updraft. Therefore, a new hail warning index was developed by using the vertical wind shear, and the index can be used to issue warnings up to 12 min earlier than achievable using traditional methods detecting increases in hailstorm intensity.