孝感市一次强降水成因及可预报性分析

Analysis on the Cause and Predictability of a Heavy Rainfall in Xiaogan City

通过对2022年7月19-20日孝感市强降水成因及可预报性进行分析,可为今后暴雨分析研究和预警预报提供参考借鉴。利用常规天气图、区域自动气象站、雷达回波等实况资料,EC等模式分析预报资料,运用天气学方法进行比较分析。结果表明:①孝感市强降水在受高层南亚高压反气旋环流控制,副热带高压加强北抬、西北冷槽东移影响的环流背景下发生的,第一阶段强降水主要是受低层暖式切变线北抬、西南急流和地面暖性低压倒槽等共同结果,第二阶段强降水主要是受低层冷式切变线、西南急流和地面江淮气旋冷锋等共同结果。②不同数值模式对500 hPa环流形势预报都比较准确,其中EC细网格最好,对低层低涡冷切系统、急流轴位置,短期预报都有体现,但位置都略有偏差。③短期降水预报中,中尺度模式比全球模式预报的量级更大、效果更好,中尺度模式中华东模式最优。指出了本次强降水过程有一定的可预报性,在环流形势上EC细网格模式预报最好,主要影响系统,如低涡冷切、西南急流都预报比较准确,但强度和位置有一定偏差。降水预报中,华东模式、CMA_3KM模式也有很好的表现。

By analyzing the causes and predictability of heavy precipitation in Xiaogan City from July 19 to 20,2022,it can provide a reference for future rainstorm analysis and research and early warning forecast.Conventional weather map,regional automatic weather station,radar echo and other real data,EC and other mode analysis and forecast data are used,and weather science methods for comparative analysis are used.The results show that①The heavy rainfall in Xiaogan City occurred under the background of the circulation controlled by the upper South Asian High anticyclone circulation,the strengthening of the subtropical high to the north and the eastward movement of the northwest cold trough.The first stage of the heavy rainfall is mainly by low warm shear line north,southwest jet and low ground inversion groove and other common results;The second stage of the heavy rainfall is mainly by low cold shear line,southwest jet and ground Jianghuai cyclone cold front.②Different numerical models are relatively accurate for 500 hPa circulation situation forecast,where EC fine grid is the best;the short-term forecast is reflected for low-level vortex cold shear system and jet axis position,but the position is slightly different;③in the short-term precipitation forecast,the mid-scale model is larger and better than the global model forecast,and the East China model is optimal in the medium-scale model.The heavy precipitation process has a certain predictability.The EC fine grid model is the best in predicting the circulation situation,and the prediction of the main affecting systems,such as the cold cut of the low vortex and the southwest jet stream,is more accurate,but the intensity and location are biased.In the precipitation forecast,the East China model and CMA_3 KM mode also have good performance.