Synoptic Characteristics of Summer Extreme Precipitation in Southeast US and East China

Extreme precipitation events associated with synoptic perturbations may trigger regional floods, causing severe socioeconomic losses. This study analyzes the synoptic characteristics of summer extreme precipitation events in the southeast US and east China, two regions of similar latitudes and geographical locations. For each region, extreme precipitation events leading to maximum regional rainfall in each summer from 1979 to 2017 are pick out, and their climatology and interannual variations are analyzed and compared with each other. Preliminary results indicate that extreme precipitation events are associated with significant synoptic forcings (potential vorticity and moisture forcing) that are 1~2 days preceding the precipitation peaks. The synoptic forcings and the diabatic heating contribute about equally to the large-scale vertical motion, indicating strong coupling between the two components. Although the background flows are quite different in the two regions, the anomalies of synoptic forcing are similar. There is significant interannual variation in the synoptic forcings, and they may contribute to the interannual variation of extreme precipitation events.