Abstract:Based on the NCEP 1°×1° reanalyzed data, the circulation situation and physics fields of two heavy snowfall events in Zhejiang during the winter of 2010 were analyzed. The results have shown that: (1) The two heavy snowfalls are caused by the intersection of north cold air and southwest warm moist flow. The duration of snowfall is short when the cold air is strong, because the front zone moves southward quickly. The heavy snowfall occurred in the convergence area of wind velocity of shear lines in the middle and low levels. (2) The cold air of moderate intensity makes the cold layer and the stationary front exist for a long time. This is an important condition for long duration snowfall. The heavy snowfall occurred in the front of low level jet on the left side. (3) There is strong convergenc of vapor flux over snowfall region. The relationships between the variation of large value area of vapor flux and the snowfall process are significant. (4) It is the favorable dynamic condition for heavy snowfall that there are convergence in the lower level and divergence in the upper level. The intensity of snowfall increases with the intensity of lower level convergence and upper level divergence.