驻马店2012年盛夏期间一次区域暴雨的成因分析

2012年8月20—21日驻马店市出现了一次区域暴雨,局部大暴雨天气过程.这次降水过程的特点是降水范围广、短时间强度大.从天气图、数值预报产品、稳定度、雷达产品等方面对这次降水过程进行成因分析,从而得出了对大暴雨预报的一些有意义的结论:暴雨的产生前要有强烈的垂直上升运动;深厚的湿云层为这次暴雨过程提供了充足的水汽条件;地面弱冷空气所致低层的偏东到东北急流为这次降水的持续提供了有利的条件.低层形成了较强的垂直切变,增强了辐合上升运动,为这次强降水提供了触发机制.新一代天气雷达监测资料分析表明,强降水天气的基本反射率强度≥45 d Bz的高度一般集中在较低的层次;暴雨要维持较长的降水时间需要一系列降水回波或多单体风暴中的不同单体连续不断经过同一个地方,或者不同移向的降水回波交叉经过同一地方,形成降水的汇集地.

A Regional Rainstorm During the Midsummer in Zhumadian in 2012

A regional rainstorm and local heavy rain occurred on Augest 20-21,2012 in Zhumadian. This processhas two characteristics,which are wide range of precipitation and strong intensity in short time. In this paper,theformation causes were investigated in terms of weather charts,NWP,stability,radar products. There are threenecessary conditions for heavy rainfall. The intensive upward motion is necessary,hygrometric stratification providesadequate moisture,and ground weak cold air causes the low eastern and northeasterly jet stream. The triggermechanism for this heavy rainfall is a formation of strong vertical shear resulting in the enhancement of convergenceupward motion. A new generation of weather radar monitoring data analysis shows the height of its intensity of basicreflectivity over 45 d Bz which concentrates in the lower level generally. Prolonged precipitation requires a series ofprecipitation echo or different monomers in multi-cell storm passing the same place,or precipitation echoes of differentmoving orientation crossing through the same place.