Based on the routine observation data,the satellite cloud images and so on,the synoptics analysis and the diagnostic analysis of physical quantity field were used to analyze the heavy snowstorm process which happened in Northeast China during March 3-5 in 2007.The results showed that the main influence systems in the process were the eastward shift and up north of southern cyclone,the combination of south and north branches upper troughs in 500 hPa.The dynamic mechanisms of heavy snowstorm formation were th...