Analysis of Mesoscale System on a Short-time Rainstorm Caused by Cold Front in Arid Area

On June 7th,2010,a short-time heavy rain occurred in the mid-north region of Ningxia,the synoptic causes of this weather process and the evolution of mesoscale system are analyzed by using the data of automatic weather station,satellite and radar images,etc.The result shows,this short-time rainstorm was caused by the interaction of influence systems,such as 500 hPa west wind trough,700 hPa shear line,vortex,low level jet,850 hPa shear line,the ground cold front etc,under the background of cold front transit and persistent circulation situation of high in the east while low in the west.The heavy rain was located in the convergence area of the left of low level jet and the end of shear line,it could be a typical characteristic of weather system of mesoscale heavy rain in Ningxia.During this heavy rain process,adverse wind area,wind field with zero line like s and front transit were the typical characteristics of radar image,and the distribution of adverse wind area was similar to the mesoscale system.