“2.28”山东罕见“雷打雪”现象形成机制分析

利用各种常规观测资料、探空资料、T639模式资料和卫星云图,分析了2010年2月28日山东境内的一次罕见"雷打雪"过程。结果表明,此次过程是在有利的大尺度环流背景下产生的。西南暖湿气流强盛,对流层低层的低空急流不断向山东输送水汽和能量;同时,近低层冷空气的侵入,迫使暖湿空气沿冷空气爬升,触发不稳定能量释放,导致强对流天气发生。850hPa低涡及地面气旋的产生,使得气旋性辐合上升增强,加强了上升运动。随着近地层温度降到零度以下,雨转雪。降水过程后期,气旋向东北方向移动,造成鲁中和山东半岛的暴雪天气。卫星云图显示,MCC是造成此次强降水的直接原因。

Analysis on Formation Mechanism of Rare ’Thundersnow’ Phenomenon in Shandong on 28 February 2010

The ’thundersnow’ weather phenomenon in Shandong on 28 February 2010 was analyzed using the routine data,sounding data,T639 model and satellite image.Results show that the process produces under the large-scale circulation background.Southwest warm and wet air flow are dominative,the low-level jet of lower troposphere continuously transports to the water vapor and energy of Shandong Province.The intrusion of cold air in lower layer at the same time forces the warm and wet air raising along the cold air to trigger the unstable energy release,whick result in the occurrence of severe convective weather.850 hPa vortex and cyclone enhanced upward motion.The rain turns to snow with ground layer temperature being below 0 ℃.Then cyclone moves to the northeast that result in heavy snow in Central and Peninsula.Combination of satellite images,it can clearly see that MCC is a direct cause of the heavy rainfall.