一次区域性雷暴大风的特征分析

Characteristic Analysis of a Regional Thunderstorm Gale

2021年8月23日午后黑龙江省西南部地区出现了一次区域性雷暴大风天气。本文利用常规观测资料和ERA5再分析资料对此次过程进行了特征分析。结果表明:该过程是在冷涡背景下,低层暖湿输送强迫形成的区域性多类型雷暴大风天气,强垂直风切变、中层干层、大的对流有效位能提供了有利的环境条件。地面辐合线触发在暖锋锋生区内产生了下击暴流和多单体风暴,造成了局地的雷暴大风和低质心强降水;线状对流系统中的弓形回波其前侧入流缺口、后侧弱回波区、高反射率因子梯度大值区、超过60 dBz的强中心不断生消及其V型缺口,都对雷暴大风和冰雹有很好的预警指示;冷池的面积与冷源强度同雷暴有明显的对应关系且对流的发展和冷池加强也形成了反馈机制。

In the afternoon of August 23,2021,a regional thunderstorm and gales occurred in the southwest region of Heilongjiang Province.In this paper,the characteristics of this process are analyzed using conventional observation data and ERA5 reanalysis data.The results show that the process is a multi-type thunderstorm gale weather formed by the warm and wet transport force at low level under the background of cold vortex.The favorable environmental conditions are provided by strong vertical wind shear,middle dry layer and large convective effective potential energy.The ground convergence line triggered the downburst and multiple individual storms in the warm front frontogenesis area,resulting in local thunderstorm gale and low core heavy precipitation.The bow echo in linear convection system has a good warning indication for thunderstorms,gales and hail,including the inlet notch in front,the weak echo area in back,the large value area of high reflectance factor gradient,the continuous generation and dissipation of the strong center over 60dBz and the V-shaped notch.The area of the cold pool and the intensity of the cold source have an obvious correspondence with the surface wind,and the development of convection and the strengthening of the cold pool also form a feedback mechanism.