2018年7月19日石嘴山暴雨过程分析

Analysis of the Rainstorm Process in Shizuishan on July 19,2018

利用常规观测资料、逐小时自动站资料、多普勒天气雷达产品及NCEP再分析资料,对2018年7月19日石嘴山地区暴雨天气过程从环流形式、影响系统、中尺度、雷达资料、物理量条件等进行了分析。结果表明,该次暴雨是在东高西低的环流背景下,由副热带高压边缘高能、高湿的暖湿气流和西风带冷空气交绥于石嘴山上空的结果。500 hPa的西风槽、700 hPa切变、低涡、低空急流是天气尺度的主要影响系统。天气尺度的抬升运动为中尺度系统的发展创造了有利的条件;从雷达反射率因子来看,2个东北西南向的带状强回波造成了该次过程短时暴雨,强回波和强降水的峰值是对应的,并且2条带状强回波和地面自动站流场分析的2条切变线相对应;强降水时段有较强的水汽输送和水汽辐合,有利于短时暴雨的形成;正涡度中心与强降水中心有很好的对应,强降水时段石嘴山处于较强的对流性不稳定区,有利于产生短时强对流天气。

Using conventional observation data, hourly automatic station data, Doppler weather radar products and NCEP reanalysis data, the rainstorm weather process in Shizuishan on 19 July, 2018 was analyzed based on circulation patterns, impact systems, mesoscale, radar data, Physical quantity conditions and the like. The results show that the torrential rain is caused by the warm and humid airflow of the high-energy and high-humidity of the subtropical high-pressure and the cold air of the westerly wind flowing over Shizuishan in the background of the east-high and low-lying circulation. The 500 hPa westerly trough, 700 hPa shear, low vortex, and low-level jet are the main influence systems of the weather scale. The uplifting movement of the weather scale has induced favorable conditions for the development of the mesoscale system. From the radar reflectivity factor, the two strong southwestern belt echoes result in the short-term heavy rain, with the good correspondence of strong echoes and the peak values of precipitation. And the two strip-shaped strong echoes are correspond to the two shear lines of the ground station automatic flow field analysis. The strong precipitation period has strong water vapor transport and water vapor convergence, which is conducive to short-term heavy rain. The formation of positive vorticity center has a good correspondence with the strong precipitation center. Shizuishan is in a strong convective instability zone during the strong precipitation period, which is conducive to short-term strong convective weather.