Causes of the First Severe Convective Weather Event in Shunde District in 2023

LU Yang; XIAO Fan; OU Yue; WAN Ziwen; LIU Shijun; WU Weizhong

doi:10.3969/j.issn.1007-6190.2025.03.008

Abstract：To analyze the physical mechanisms of the severe convective processes,phased-array radar observations and ERA5 reanalysis data(0.25°×0.25°)were used to investigate the causes of two weather events that occurred in Shunde on March 24-25,2023.The results show that during the event on the 24 th,the upper-level circulation was in a post-trough pattern,with trough axes at high and low levels exhibiting a forward-tilted configuration.The intrusion of cold air into an unstable atmosphere characterized by"warm below and cold above"and"dry above and moist below"was the main cause of the localized severe convec-tive weather.The event on the 25th was a typical warm-sector heavy rainfall south of a front.The prolonged confrontation between warm and cold airflows led to the continuous formation of new convective cells near the surface convergence line,resulting in a"train effect,"which was a key factor in the heavy rainfall.Addi-tionally,strong convective instability,intense vertical wind shear,a sharp increase in VIL(Vertically Inte-grated Liquid)within a short period,suitable heights for the 0 ℃ and-20 ℃ levels,and favorable dynam-ic lifting conditions all contributed to the hail occurrence on the 24th.However,the short duration of con-vective cell influence,a maximum VIL of only 32-38 kg·m-2,low CAPE(Convective Available Potential Energy)values,and the absence of sustained and powerful updrafts to support hailstone growth were impor-tant factors limiting the hail size.This study provides a scientific basis for the forecasting and early warning of severe convective weather in the Shunde district of Foshan,contributing to a better understanding of the mechanisms behind warm-sector heavy rainfall and severe convective weather.It holds significant practical importance for disaster prevention and mitigation efforts in South China.