2009年11月石家庄暴雪天气过程诊断分析

利用常规观测资料和NCEP资料,对2009年11月9—12日石家庄特大暴雪进行分析。结果表明：暴雪过程与高空西槽、河套地区南部南支槽以及中低空切变有着密切联系。高低空急流的较好配合利于暴雪区内上升运动的加强,上升区始终位于高空偏西急流右侧的辐散区内及低空西南急流出口区左前部的辐合区内,且700 hPa北支西北急流对暴雪的增强有着至关重要的作用;上升运动与正涡度区相对应,垂直上升最强区与正涡度中心相吻合;上升运动与湿度场的交汇对暴雪的发生及加强显著,石家庄上空自地面至200 hPa维持一相对湿度为90%的高湿柱,西南气流带来的南方暖湿气流及东北回流带来的渤海湾高湿大气是产生大暴雪的能量及水汽源地。

Diagnostic analysis of a heavy snow process in November of 2009 in Shijiazhuang

Based on the conventionally observational data and the NCEP data,a heavy snow process during November 9-12,2009 in Shijiazhuang was diagnosed.The results indicate that the heavy snow process is related to upper western trough,southern trough in the south of Hetao area and shear in the middle and lower level.The vertical allocation of the upper and lower level jet is favorable to the strengthening of ascending movement in the heavy snow area.The ascending area is always located in the divergence area on the right side of upper westerly jet and the convergence area in the front of left side of lower southwest jet exit,and the northwest jet in the north of 700 hPa plays a very important role to the strengthening of the heavy snow.The ascending region has a better correlation with the positive vorticity field,and both locations of the strongest ascending region and positive vorticity center are consistent.The better correlation between the ascending motion and humidity field is important to the occurrence and reinforcement of the heavy snow.There exists a high relative humidity（about 90%）column from the surface to 200 hPa over Shijiazhuang.The south warm-wet southwest air airflow from the southwestern and the wetter stream of the Bohai bay from the northeast return streamer are the source of energy and water vapor.