Analysis of a short-time heavy rainfall in southeast of Jilin province on July 31,2010

Based on the real-time observational data from the dense weather stations,the NCEP reanalysis data with 1°× 1° resolution and Dopplor radar data in Baishan,a short-time heavy rainfall process on July 31,2010 in the southeast of Jilin province was analyzed.The results show that a small short-wave disturbance appears in 500 hPa flat front area accompanied by severe connective weather.The thermal vertical structure which is cold in upper level and warm in low level is favorable to lifting of low level convergence.Precipitation does not occur when convergence lifting caused by wind field only exists in the bottom,so one must pay attention to the structure change of the whole field wind.Water vapor is from accumulation of prophase precipitation,and lacking water vapor transportation is one of the main reasons that this rainfall lasts in only short period.The invasion of small stock cold air in the high energy region is the trigger origin of heavy precipitation.The location of strong rainfall falling area corresponds to that of the high energy area invaded by cold air,and so is the period of the heavy rainfall and the process that the K index decreases from the maximum value,then unstable energy releases quickly.The intensity and gap of radar echo,the intensity of radical velocity,zero velocity line shape,and headwind area are indicative to the heavy rainfall.