2014年8月发生于温州市的一次大暴雨过程分析

对2014年8月19日08:00至20日08:00温州市大暴雨过程做技术总结. 通过对500 hPa环流分析，利用欧洲中心850 hPa和1 000 hPa细网格风场产品以及雷达拼图、实况雨量分析发现，该次过程为高空槽和低层偏南风急流控制下的系统性强降水，降水的时空分布极不均匀.该次降水过程分为19日白天和夜间2个时段，19日白天的暴雨过程由低层850 hPa中尺度辐合线所造成，辐合线上，有较强的风速辐合.19日夜间的暴雨过程由1 000 hPa风向和风速的辐合造成.该次降水过程降水时段集中、雨强强、累计降水量大.通过分析各家模式降水产品，总体来说，各家对于此次降水强度和落区的把握均较差，即使中尺度系统的位置预报正确，但对极端短时强降水(如3 h降水≥100 mm)的预报尚有较大误差.

Process analysis of a heavy rainfall happened in Wenzhou in August, 2014

We make technical summary of the heavy rainfall in Wenzhou that happened during 08:00 on August 19 to 08:00 on August 20, 2014. After analysis of 500 hPa circulation, using 850 hPa and 1 000 hPa fine grid wind field products of European Center as well as the analysis of radar mosaic and live rainfall, we find that this process is systematic heavy precipitation caused by trough and low level southerly jet, and the temporal and spatial distribution of precipitation is extremely uneven. This process can be divided into two periods:the day and night on 19th. The process of heavy rain in 19th day is caused by the mesoscale convergence line at 850 hPa with strong wind speed convergence in the line, while the process of heavy rain at 19th night is caused by the convergence of wind direction and wind speed at 1 000 hPa. This process is concentrated on strong rain, and the cumulative rainfall is large. By analyzing products of precipitation that from various models, overall, we find that the prediction of intensity and falling area are relatively poor for Wenzhou. Even if the forecasting of location of mesoscale system is correct, the prediction of extreme short time heavy rainfall (such as precipitation ≥100 mm of 3 h) is still relatively difficult.