山东一次罕见“雷打雪”天气形成条件分析

Analysis of Formation and Development Condition for a Rare "Thunder-snow" Event in Shandong

利用常规观测、地面加密自动站以及卫星云图、多普勒天气雷达资料,对2010年2月28日山东省罕见"雷打雪"天气的发生发展条件进行了分析。结果表明:此次过程是在高空槽、切变线低涡、强低空西南急流及冷锋等天气系统相互作用下产生的;强对流天气发生前,对流层整层出现持续异常增温,为"雷打雪"提供了充足的能量积累;低空急流的建立为强降水区提供了充分的水汽供应;强对流天气发生在大气层结不稳定、冷锋携带冷空气南下的过程中;MCC是造成"雷打雪"过程的直接原因,冰雹、雷暴等天气出现在TBB低值中心及云团移动前沿TBB等值线密集区;雷达基本反射率因子图上出现"人"字形回波及强回波中心,地面形成中小尺度风速风向辐合区,对强对流天气落区预报有一定的指示意义。

The paper analyzes the formation and development of an unusual ＂thunder-snow＂ event on 28 February 2010 in Shandong province by using the conventional data,intensive observation of automatic weather station,satellite images,Doppler-Radar data etc.The results show that interaction of westerly trough,vortex with shear line,strong southwesterly low-level jet and cold front resulted in the event.Before the severe convective weather,there was unusual sustained increasing of temperature in troposphere,which provided sufficient energy accumulation for the occurrence of ＂thunder-snow＂.The low-level jet supplied sufficient water vapor for the strong precipitation area.The occurrence of severe convective weather attributed to unstable atmospheric stratification and cold front with cold air moving southwards.MCC was the direct cause which leads to ＂thunder-snow＂ event,and severe weather such as hail and thunderstorm emerged in the great negative value center and isoline dense areas of TBB in front of moving cloud clusters.The band echo with the shape of ＂人＂ and its strong center detected from the PPI screen and the meso-and micro-scale convergence zone of wind speed（direction） in ground layer had a certain significance to forecast distribution of strong convective weather.