德州市一次春季暴雪过程诊断分析

利用常规气象资料、micaps3.2数值模式产品剖面图和多普勒雷达资料,对2013年4月19—20日发生在德州市的春季暴雪天气过程进行了综合诊断分析。结果表明:此次暴雪天气过程的主要影响系统是低槽东移时与北方冷空气结合而形成的回流降雪,暴雪产生在500~700 hPa槽前西南气流的前部、850 hPa东南风与东北风的辐合区域;中上层的西南风急流和低层的东南风气流为暴雪的产生提供了源源不断的暖湿空气,高层辐散、低层辐合以及较强的上升运动为暴雪的产生提供了有利的动力条件;此外降水相态与850 hpa的温度场(-4℃线)对应较好,同时925 hPa气温低于0℃、地面温度低于2℃或者0℃层高度明显低于925 hPa也可以作为雨雪相态转换的判据之一。

Diagnostic Analysis on a Spring Blizzard in Dezhou City

Using conventional meteorological data ,micaps 3.2 numerical model product profile and doppler radar data ,a spring blizzard weather process in Dezhou City on April 19th to 20th ,2013 was integrated diagnosis analyzed. Results showed that the main influencing system of the blizzard weather process was low trough eastward with the north cold air to form a backflow snow ,blizzard produced before the trough of the southwest airflow between 500 hPa and 700 hPa ,and convergence area of southeast and northeast wind of 850 hPa. Upper-middle-class southwest jet and the low-level southeast blast provided a steady stream of warm moist air for blizzard′s production. High-level divergence ,low-level convergence and strong upward movement provided the favorable dynamic conditions for blizzard. In addition ,precipitation phase and 850 hPa temperature （-4℃line） corresponded well. It could be used as one of the phase transformation and criterion that the 925 hPa temperature was lower than 0 ℃,the ground temperature was lower than 2℃,and 0℃layer height was significantly below 925 hPa.