The climatic feature of precipitation over 10 mm in Ningxia region in recent 49 years were analyzed by using daily precipitation data of 20 meteorological stations from 1961 to 2009. The results show that weather events with precipitation over 10 mm increased gradually with the variety of terrain from north to south, and the amount of the events in the loess hilly region of the south was double more than that in the irrigated area. Moderate rain contributed greatly to rainfall and rainstorm increased gradually. By the statistics of rainfall intensity, the frequency of rainfall more than 1.0 mm/h but less than 2.0 mm/h was the most, and more than 4.0 mm/h was the least in Ningxia, both the frequency of rainfall more than 3.0 mm/h but less than 4.0 mm/h and that less than 1.0 mm/h were gradually increased since the 1980s. The years with extremely more weather events with precipitation over 10 mm in Ningxia are 1961,1964,1985 and 1990.

Based on analysis of characteristics of atmospheric circulation and physical quantity fields on each layer, aswell as hourly satellite images, the causes of a heavy snowstorm p rocess in mountainous region of south Ningxia from 17 to 18 October in 2002 was studied. Results show that three air currents on middle and low layers p lay an important role in this p rocess, and low vortex and warm shear line are key influencing systems, and vapour transport comes p rimarily from the low layer. The study also reveals the fact that meso -microscale system is active in the heavy snowstorm p- rocess.

By using the conventional meteorological data，a meteorological analysis on the large scale circulation background，the synoptic scale influencing systems，the hourly evolvement of satellite cloud image and the atmospheric stratification stability that caused the formation and the development of the meso - α - scale convective system，which caused the severe convective weather process on May 30，2005，was done in this paper；and based on the physical quantity products of T213 numerical weather forecast model，a dynamic analysis on the distribution of physical quantity fields of the system was also done. The results show that under the favorable conditions of temperature and humidity and dynamic factors，such as the Mongolia cold vortex rotating and moving eastwards and southwards，the existence of both the high - level and low - level jet stream，the warm and wet tongue extending in the low layer，the cold and dry tongue in the middle layer，and the large area convective instability，several meso - γ - scale convective systems were excited，then they united into several meso - β - scale convective systems，eventually，the meso - α - scale convective system was formed by the coalition of the several meso - β - scale convective systems.

 A 2 day’、continuous severe thunderstorm occurred in most areas of Ningxia on June 14th and 15th, 2004, part of the ye110W  RlVer  1TTlgatlOn TeglOn haS heen StrLICl} by hall.  By LISlng the TOlltlne meteOTOlOg1Ca1 data and dOppleT radar pT0(1LICtS and  SO On,a meteorological analysis of this process has been done, the analysis shows that: this is a typical continuous severe thunderstorm pro-CCSS In  N1ngXla Wh1Ch TCSlllted fTOm the TOtatlOnal eaStWa.T(1S and  SOLIthWa.T(1S  MOngOha Cold  VOrteX.  Frnm  the radar eC110  dlffeTenCe  he-tWCen  general  thLIndeTStOTm  and  SCVCTe  thLIndeTStOTm  Wlth  hall,  the  mOnltOTlng  and  fOTCCa.Stlng  1ndeX  Of  N1ngXla  SCVCTe  COriVCCtlOn
weather has been gained with statistics. By using the forecasting products of Ningxia meso一、tale model MMS, a simulative analysis
has been done on it's related physical quantities, which has gained a valuable results.

Based on routine weather materials and T213 numerical prediction product , the main influence system and the physic
quantities prediction field related to T213 numerical forecast of the first soaking rain process which occurred on May 5 to 6 in 2003 i
Ningxia were analyzed in this paper. The results show that T213 has excellent prediction ability and direction sense to the precipita
tion in Ningxia, and its credibility is improving constantly with shortening of the forecast prescription.

By using routine meteorological data，numerical forecast products，satellite cloud photographs and radare choes，applying synoptic analysis and diagnostic analysis methods，We analyzed the infrequent regional heavy rain which occurred in Ningxia on June7~8th,2002.The results show that this heavy rain occurred under the favourable weather condition that the high center in the east whilethe low center in the west，this is a typical mixed precipitation weather.The main impact system is cold trough on 500 hPa，low eddy shear line on 700 hPa，low ertroposphere jet in the southwest and surface occluded front.The relative stable condition which blocked in the east and the maintain of the southwest lower troposphere jet were the main reasons of this hard rain’s maintain