萍乡市一次区域性大暴雨漏报原因分析

Analysis on the Reason of Missing a Regional Heavy Rain in Pingxiang

利用常规观测资料、加密自动站资料对萍乡市2015年5月的一次区域性大暴雨过程漏报的原因进行了分析,分析表明此次过程漏报原因主要是:1)没有注意到925 h Pa萍乡中部的强温度锋区; 2)忽视了中高层干冷空气扩散南下的影响; 3)误认为低层辐合条件偏弱。利用EC细网格(ECMWF-thin)资料计算此次过程中的一些物理量,对暴雨预报做进一步的诊断分析。分析结果与总结的漏报原因吻合:萍乡市中部低层存在的广义位温的高值中心表明萍乡市中部和北部之间确实存在明显的温度锋区;湿热力平流参数正负中心的交界面证明了萍乡市北部有明显的锋生,锋生是中层干冷空气补充南下叠加在低层高温高湿区上造成的;热力垂直螺旋度和水汽垂直螺旋度的分析则表明低层的水汽和热量辐合条件是较强的。

By using the conventional observation data and the encrypted automatic station data,this paper analyzes the reasons for missing a regional torrential rain in May 2015 in Pingxiang.The analysis shows that the main reason for missing this process is that:1)no noticing 925 hPa strong temperature front in central Pingxiang;2)neglecting the the spread of dry and cold air in the middle and upper reaches of the south;3)we think that the convergence condition of the lower level is weak.Using European high-resolution data to calculate some physical quantities in this process,the rainstorm forecast is further diagnosed and analyzed.The results of the analysis are consistent with the reasons for missing this process.The value high center of generalized potential temperature at the lower level in the middle of Pingxiang City indicates that there is an obvious temperature front between the middle and north of Pingxiang City,and the interface between positive and negative center of the wet thermal advection parameter shows that there is obvious frontal growth in the north of Pingxiang.The front generation is caused by the dry and cold air replenishment in the middle and superimposed on the low temperature and high humidity area,and the analysis of the thermal vertical helicity and the water vapor vertical helicity shows that the water vapor and heat convergence conditions in the lower layer are stronger.