Statistical characteristics of rainstorms caused by southwest vortex with shear line in Guizhou

To further understand the influence and importance of southwest vortex with shear line on the rainstorms in Guizhou, the characteristics of southwest vortex with shear line and rainstorms in Guizhou caused by southwest vortex with shear line in recent 14 years were statistically analyzed by using the daily precipitation data from 84 national meteorogical observation stations in Guizhou Province, the MICAPS regular observation data, FNL1°×1 ° reanalysis data from April to October between 2010 and 2023. The results showed that: (1) in recent 14 years, southwest vortex with shear line primarily generated at night, with 60% moving eastward and 40% moving southeastward. The highest frequency of vortex sources was from Xiaojin, followed by Jiulong. (2) About 70% of southwest vortex with shear line affecting Guizhou moved to the southeast, mainly affected the west-central region of Guizhou after they moved southward from southern Sichuan. Vortices originating from the Xiaojin vortex source and Jiulong vortex source were more frequent with comparable frequency, and their occurrence in June was obviously more than that of other months. (3) In recent 14 years, over 30% of regional heavy rain events in Guizhou were caused by southwest vortex with shear line, which was the leading influencing system. In addition, these events were primarily caused by southwest vortex with shear line moving southeastward. The heavy rainfall centers caused by southwest vortex with shear line were mainly located near the Beipan River in western Guizhou, followed by Leigong Mountain in the southeast. The most frequent heavy rainfall events occurred in June, followed by July.