2018年4月桂西南一次冰雹天气过程诊断分析

Diagnosis and Analysis of a Mixed Strong Convective Weather Process in Southwest Guangxi in April 2018

利用常规气象观测资料和NCEP(1°×1°)再分析资料对2018年4月14日下午—15日凌晨左右发生在桂西南的一次强对流天气过程进行分析,结果表明:此次强对流天气过程具有持续时间长、影响范围广、小时雨强较大、前期以降雹为主、后期以短历时强降水为主的特点;近地层锋面和辐合线是此次强对流天气发生的重要触发机制;200 hPa高空辐散流场有利于底层辐合上升运动的加强,可以弥补500 hPa弱槽槽前动力抬升机制的不足;对流层中层具有干冷空气的侵入是预报强对流天气的关键因子,而地面强对流天气容易发生在干空气侵入700 hPa层之后数小时内;强对流天气容易发生在θse大值区或者舌区;对流层正涡度从中层下传到底层对于预报强对流天气的出现具有一定的指示意义;雷达产品分析表明回波具有明显的悬垂回波、弱回波区、辐合区、中气旋、三体散射长钉和旁瓣回波特征。

Based on conventional meteorological observation data and NCEP(1°×1°)reanalysis data,a severe convective weather process in southwestern Guangxi from the afternoon of April 14 to the early morning of April 15,2018 was analyzed.The results show the severe convective weather process has the characteristics of long duration,wide range of influence,large hourly rainfall intensity,hail in the early stage and short duration heavy rainfall in the later stage.Near-surface fronts and convergence lines are important triggering mechanisms for the occurrence of severe convective weather.The 200 hPa high-altitude divergent flow field is conducive to the enhancement of bottom convergence upward motion,which can make up for the deficiency of dynamic lifting mechanism in front of 500 hPa weak groove.The intrusion of dry and cold air in the middle troposphere is the key factor for predicting strong convective weather,while the strong weather on the ground tends to occur within hours after the intrusion of dry air into the 700 hPa layer.Strong convective weather tends to occur inθse region or tongue region.The downward propagation of positive tropospheric vorticity from the middle to the bottom is of certain significance in predicting the occurrence of severe convective weather;Radar product analysis show that the echo has obvious characteristics of hanging echo,weak echo area,convergence area,mesocyclone,three-body scattering pin and sidelobe echo.