Extreme Heavy Rainfall and Environmental Characteristics of the Remnant Vortex of Typhoon"Haikui"(2311)

WEN Yingfang; XIAO Ting; ZHAO Shimei

doi:10.3969/j.issn.1007-6190.2025.04.002

Abstract：To enhance the understanding of extreme heavy rainfall associated with typhoon remnant vor-tices,this study analyzes the extreme heavy rainfall event induced by the remnant vortex of Typhoon"Haikui"in Guangdong,using precipitation data from national and regional automatic weather stations and ERA5 reanalysis data.The results show that:(1)The most intense rainfall occurred from the night of the 7th to the daytime of the 8th.Multiple stations in the Pearl River Delta region recorded exceptionally extreme precipitation,with Donghu Street in Shenzhen and Hecheng Street in Foshan breaking local historical records for 12-hour and 24-hour rainfall.(2)The stable maintenance of synoptic-scale systems,including the conti-nental high to the north of the remnant vortex and a deep cold vortex to the northeast,provided favorable background conditions for the extreme rainfall.A southeasterly low-level jet-formed by the convergence of easterly return flow and southerly monsoon winds-delivered highly favorable moisture,thermal,and dynamic conditions.(3)The anomalies in dynamic and moisture conditions were remarkable,with the maximum low-level dynamic convergence intensity and moisture flux divergence reaching over 5σ in standardized anoma-lies.This study provides critical insights into the mechanisms of extreme rainfall associated with typhoon remnant vortices,aiding in improved forecasting and disaster mitigation for such high-impact weather events.