为了更好地认识山西省北部区域暴雨形成机制，为防灾减灾提供精细化的预报信息，利用常规地面和高空探测资料、NCEP/NCAR 1°×1°再分析资料、加密自动气象站资料以及FY-2E卫星TBB资料，对2012年7月20日20时—21日20时山西北部区域暴雨过程进行诊断分析。结果表明：（1）这次暴雨发生在200 hPa高空西风急流稳定加强、500 hPa阻塞背景下，低空低涡切变线是其主要影响系统，低空西南急流偏西偏北是其重要原因之一。（2）雨区上空对流层低层大气处于强对流不稳定状态，高层强的干侵入和低层弱北风的侵入是触发不稳定能量释放的重要机制。（3）地面自动站风场信息显示主要触发系统有中尺度涡旋、辐合和切变3种类型，3种类型造成的降水强度和持续时间均不同。（4）500 hPa垂直螺旋度的变化可表征强降水系统的发展和移动，而考虑水汽因子后的水汽垂直螺旋度能更好地反映雨区上空对流层中低层的动力场结构特征，对预报强降水落区和移动有很好的指示意义。

In order to better recognize formation mechanism of regional rainstorm in northern Shanxi Province, and provide fine forecasting information for disaster prevention and mitigation, based on conventional meteorological data, NCEP reanalysis data and the intensive observation of automatic weather station data, combining black body temperature data of FY-2E meteorological satellite, a torrential rainfall in northern part of Shanxi Province during 20-21 July, 2012 was diagnosed and compared. The results showed that: (1) the rain storm happened in 200 hPa upper-air westerly stablility strengthening, 500 hPa blocking background, low vortex with shear was the main system, low level southwest jet location north of the west was one of the important reasons. (2) The rain area above the troposphere, the lower atmosphere was in the convective instability state, tall strong dry intrusion and low weak northerly wind invasion were important mechanisms for triggering instability in energy release. (3) Analysis of automatic wind field information displayed main trigger systems that had included three patterns, such as mesoscale vortex, mesoscale shear, and mesoscale convergent which caused different precipitation intensity and duration. (4) The negative area of vertical helicity in 500 hPa showed the development and movement of heavy precipitation system. The water vapor vertical helicity, with considerd effect of water vapor, described the dynamical field of the middle-lower troposphere over rainfall region more clearly, and was a good predictor for the area and movement of heavy rain.