Meso-scale Convective Characteristics of "7·22"Extreme Rain in the West Mountainous Area of Fujian

An extreme severe rain occurred in the west mountainous area of Fujian on 22 July 2015, with the precipitation of 254. 9 mm for 6 hours and the maximum total precipitation of 295. 5 mm. Using conventional observations, automatic weather station data,satellite data,wind-profiling radar and CINRAD-SA Doppler radar data, this extreme severe precipitation is analyzed focusing on the environmental conditions and structure characteristics of the meso-scale convective system(MCS). Results show that predominate influencing systems are the low-level shear line and the upper trough between subtropical high and the anticyclone over Yunnan and Guangxi. The reinforcement of unsteady convective stratification,decrease in the level of lifting condensation and free convection, high atmospheric precipitable water and weak vertical wind shear over the rainstorm-hit area are all favorable to the development of MCS. The initial convective cloud develops on the edge of Guangdong and Fujian. Convective cells develop strongly with