Abstract: In order to investigate the causes of winter freezing weather and improve freezing rain forecasting accuracy, synoptic characteristics of a freezing event in February of 2010 in Anhui province were analyzed based on conventional observation data, intensive observation data and the NCEP reanalysis data.At the same time, numerical simulation by a WRF model for this process was performed, and physical field and stratification condition were discussed.The results show that freezing rain in the south mountain area and north plain area of Anhui province is mainly caused by strong cold air moving down south quickly, which makes cold continental high meeting the western Pacific subtropical high and forming a saddle shape pressure field.Analysis of simulation suggests that forming reasons and stratification features of this process in the mountain and plain differ significantly.Forming of freezing rain in the mountain area is related to block and lifting of mountain to cold and warm air, while it needs strong cold air moving southward rapidly in the plain area and produces stratification structure that is favorable to generate freezing rain weather.In the mountain area, it has great temperature inversion gradient and higher cold center height when freezing rain weather occurs.In the plain, it has great negative temperature center and higher cold center height near the surface when freezing rain weather occurs, while there is not stable corresponding relation with temperature inversion gradient.Generation of freezing rain weather is a complex physics process, and it has relationship with intensity of temperature inversion, height of cold pad and amplitude of temperature change.

Key words: Freezing rain, Weather Research Forecast(WRF) model, Temperature inversion layer, Numerical simulation