银川平原极值暴雨天气水汽预报着眼点

利用常规气象资料和NCEP／NCAR全球再分析逐日网格点（2．5°×2．5°）资料，对宁夏银川平原地区两次典型极值暴雨天气的水汽条件进行分析，以期总结出银川平原极值暴雨水汽预报着眼点．结果表明：两次区域性极值暴雨均发生在中纬度“两槽一脊”的环流背景和“东高西低”的环流形势下；两次过程水汽的汇集和辐合均表现出突发性，可在过程发生前12h甚至更短的时间内完成；水汽输送通道的移动方向和移动速度分别对暴雨落区和降水强度有较好的指示意义．宁夏南部暴雨天气水汽；15集突发性特征表现不明显，可能的原因是宁夏南部地势较高，南北部海拔高度落差较大和银川平原西侧贺兰山的共同作用，水汽在经过爬坡之后迅速汇聚辐合，导致了这种水汽汇聚的突发性．

Yinchuan Plain Extreme Rainstorm Water Vapor Forecast Focus

Using meteorological data and the daily NCEP/NCAR reanalysis data(2.5°×2.5°lat/1on),we analyzed the vapor conditions of the two typical extreme rainstorm in Ningxia Yinchuan plain,hoping to summarized Yinchuan plain extreme rainstorm water vapor forecast focus.The result showed that the two regional extreme rainstorm both occurred in mid-latitude of "two troughs and one ridg" circulation background and the "high east and low west" circulation situations.The two processes of water vapor collected and convergence all represent sudden,it can finished even shorter 12 hours before the course take place,but in southern Ningxia the sudden characteristic of water vapor collection in a torrential rain is not obvious,the reason probably is southern Ningxia on higher ground,the interaction between the large drop of north and south elevations and Yinchuan plain on the west side of Helan mountain,water vapor rapid gathering convergence after climbing,it lead to the sudden of the water vapor.The results also showed that water vapor transport channel’s moving direction and moving speed has good instruction significance to distribution of rainstorm centers and precipitation intensity.