新疆2017年5月一次大降水天气过程诊断分析

Diagnostic Analysis of a Heavy Rainfall Process in Xinjiang in May 2017

利用常规气象观测资料,分析新疆地区2017年5月18—20日大降水天气过程环流形势,水汽、动力和热力条件及卫星云图演变等,揭示大降水天气成因。结果表明:500 hPa中高纬度一脊一槽、后期南北两支槽结合是此次大降水过程环流背景和天气学条件;槽前西南气流持续水汽输送及低层水汽辐合,低层辐合高层辐散,加上地形抬升作用,是大降水有利水汽及动力条件;前期北疆各地气温较高,蓄积有利热力条件;中尺度对流云团发生发展不断经过同一区域,维持较长时间降水。

Based on the conventional meteorological observation data,the circulation situation,water vapor,dynamic and thermal conditions and satellite cloud picture evolution of heavy precipitation weather process in Xinjiang from May 18 to 20,2017 are analyzed to reveal the causes of heavy rainfall.The results show that the circulation background and synoptic conditions of the heavy rainfall process are as follows:500 hPa mid high latitude one ridge and one trough,and the combination of North and South Branch troughs in the late stage;the southwest airflow in front of the trough is the favorable water vapor and dynamic conditions for the large precipitation,such as continuous water vapor transport and convergence in the lower layer,convergence at the lower level and divergence at the upper level,and topographic uplift;Mesoscale convective cloud clusters continue to pass through the same area and maintain precipitation for a long time.