Abstract:Using upper and lower weather chart data, sounding data, radar and satellite data, the cold airflow snowfall events which happened in recent 10 years in Shanghai area were studied and the mechanism for this kind of weather was preliminarily revealed. The conclusions are as follows: there are total 12 cold airflow snowfall events over the year 2000 to 2009 in Shanghai area, which take up a proportion of 25% of the whole snowfall weather days for recent 10 years in Shanghai area. Most of the events, when the snowfall is notable, happened to have a trough behind Shanghai area on the 500 hPa weather chart. Before the cold airflow snowfall, the stratification in the low layer of the sounding data at Baoshan Station was often unstable, and it was usually very moist between 850 and 925 hPa levels. On the satellite image of cold airflow snowfall, the cloud which has a shape of white bright wavy structure and a height below 3000 m, goes in the same way as the trend of coastline. Radar reflectivity was very weak, usually less than 35 dBz for most of the cold airflow snowfall events, and the difference in temperature between sea surface and 850 hPa level was 10 to 14℃, while on the 925 hPa level the difference was 8 to 11℃. The wind direction of Baoshan Station was NW WNW N and wind speed was 3—6 m·s-1 during cold airflow snowfall. Compared with Shandong Peninsula, the cold airflow snowfall in Shanghai area has a smaller range, shorter duration and lower intensity because of its special geographical position and topographic condition.