宁夏中北部一次(2009-11-10)大到暴雪天气诊断分析

Diagnostic analysis of a heavy snowstorm on 10 November,2009 in north central regions of Ningxia

针对宁夏中北部地区一次(2009-11-10)大到暴雪天气过程,利用常规天气及数值预报产品资料,从天气形势及物理量诊断两方面对该次暴雪的成因进行了分析.结果表明,500hPa西风槽,700hPa低空急流、切变,地面倒槽是该次过程的主要影响系统;高低层散度的有力配置及高低空急流的耦合作用是该次过程的动力原因;充足的水汽条件和不稳定能量的积累以及高空西风急流、低层偏南风急流、近地层偏东风急流的共同作用是该次暴雪产生的根本原因.从各家数值预报场的预报情况来看,日本及NCEP的降水量预报对大到暴雪落区及降水量有明显的指示意义。

For the blizzard weather process on 10 November,2009 in north central regions of Ningxia,using conventional weather information and numerical prediction product,the causes of the blizzard forming were analyzed form two sides of synoptic situation and diagnose of physical quantity.The results indicate that,the main influence system of the weather process was the westerly tough on 500 hPa,low level jet stream and shear line on 700 hPa,and ground inverted trough.Strong configuration of high and low level divergence and the coupling action of high and low level jet stream is dynamic reason for the process.The root cause of producing the heavy snowstorm is the combined effect of which is adequate moisture conditions and instability in the accumulation of energy and high-altitude westerly jet,low-level southerly jet,near ground easterly jet.Numerical forecast products from Japanese and NCEP provided good indication to the heavy snowstorm.