开封市暴雨天气过程预报着眼点分析

Forecast Analysis of Rainstorm Process in Kaifeng City

为进一步提高暴雨大暴雨预报预测能力,从天气预报实践工作角度出发,利用常规气象资料和数值预报产品分析2016年7月19~20日开封市暴雨天气过程。结果表明,南亚高压发展北上,西太平洋西岸的副热带高压西伸,对流层低槽东移发展成高空低涡,配合地面气旋,东移北上的过程中产生了暴雨天气过程;强降水前湿层很厚,达到400hPa,西南低空急流和东南低空急流提供了良好的水汽通道和能量输送;水汽辐合来自对流层中低层,尤其是850、925hPa贡献最大,位于低涡中心及其切变线附近和低空急流的出口区;强水汽辐合略早于强降水,对强降水有预示作用;强降水前及过程中,暴雨区位于假相当位温和对流有效位能(CAPE)高值区,强降水时段500hPa与850hPa假相当位温差为负值;地面辐合线及强辐合中心为暴雨的产生提供了触发条件。研究成果可为暴雨及大暴雨预报提供参考。

In order to further improve the forecasting ability of heavy rain,from the perspective of weather forecasting practice,the conventional meteorological data and numerical forecast products were used to analyze the rainstorm weather in Kaifeng from 19 to 20July 2016.The results show that South Asian high-pressure developed northward;the subtropical high at west pacific bank moved westward;the troposphere low trough developed eastward into a high-altitude vortex,and the rainstorm is produced in the process of the vortex moving northeastward with the ground surface cyclone;the wet layer thickness increased to 400 hPa before heavy precipitation;southeast and southwest low-level jet stream provide a good water vapor channel and energy transport;the convergence of water vapor comes from the middle and lower troposphere,especially 850 and 925hPa,which is located at the center of the low vortex and near the shear line and the outlet of low level jet stream;strong water convergence appears earlier than rainstorm which means a significant effect on heavy precipitation;the troposphere is located at the high-value area of Qseand CAPE before and during the heavy rain,and the Qse500-Qse850 is negative;ground convergence line and strong convergence center provide the trigger conditions for the heavy rain.The research results can provide reference for heavy rain forecasting.