The Doppler Weather Radar Analysis of a Heavy Snow Event
Based on the conventional and singleDoppler radar data，the heavy snow event o ccurred in the North China on 6th February 2006 has been analyzed. The results s how that the major influencing system of this heavy snowfall is the wellmatche d configuration of the trough at 500hPa, the herringbone shear at 850hPa and the cyclone at surface. The Doppler radar data analyses show that the appearance of the mesoscale inverse shear at 0.7～1.1 km, as well as the establishment an d downward stretch of the southwestern jet at 4.8km accelerated the wind convergen ce and thickening of the convergence layer, which provide favorable condition to the heavy snowfall. The timings of the mesoscale inverse shear and t he southwestern jet correspond well to that of the appearance and maintenance of the heavy snowfall. The cold front also affects t he maintenance of the snowfall. We applied the improved EVAD technique to dynami cally analyze the changes of the average divergence and vertical velocity at dif ferent snowfall periods. The results indicate that the appearances of the meso scale inverse shear and the cold front correspond to the intense convergence and upward motion, which cause the occurrence and maintenance of the snowfall. Thes e further confirm the existences of the mesoscale inverse shear and clod front , as well as their correspondence to the heavy snowfall.