Abstract:Using NCEP/NCAR reanalysis data during 25—29 Jan. 2008,we have analyzed the physical quantities including the circulations for weather background, divergence field, vertical velocity field, streamfunction along with the potential velocity of water vapor transport, and the Q vectors during the heavy snow process as observed in Jiangsu province. The comparison of features of those physical quantities in southern part of Jiangsu, where the snow center is located, with those in the northern part of Jiangsu has been made. Our results have demonstrated that the falling area of snow can be identified well by the positive value of differences of the divergence of wind at 200 hPa with that at 850 hPa, which is meaningful for us to predict the place where the snowstorm will occur. The significant moisture convergence, along with the anomalies of cold air that appear around Yangtze River and southern of Jiangsu, is one of the important factors determining the continuous heavy snowfall over the Yangtze-Huaihe Valley. The Q vector convergence area caused by ageostrophic wind which is located in shear line at 850 hPa possibly provide a favorable condition for this heavy snowfall process.