The Analysis on the Weather Process of Snowstorm in the Middle and North Region of Ningxia Province

From 0800H,March 2th to 2000H,March 3th,2007 there were a pleasant fall of snow in Ningxia Province.The snow fall changed from 3.0mm to 18.3mm.The heavy and snowstorm appeared in the middle and north of Ningxia Province.The 12h and 24h snow fall was maximal in Ningxia for recent 30 years.The weather circulation background,effect system and the development of meso-scale and micro-scale weather systems were analysed by using conventional meteorological information,Ningxia numerical measure of the localization of MM5 forecasting model products,Doppler radar detection of information,satellite cloud.The results showed :the snowstorm possessed obvious feature of meso-scale and micro-scale weather systems.The main effect system was the ground-based hot inverted though,500hPa southwest warm-moist air and,700hPa Lanzhou low vortex,and Ground meso-β scale that provided advantageous vapor and dynamic for the snow fall.