Based on the meteorological observation data and NCEP/NCAR reanalysis data,this paper analyzes the characteristics and causes of an infrequent snowstorm process accompanied by thunderstorm occurred from 18 to 19 February 2013.Results show that the strong 700 hPa southwest airflow and the obvious 925 hPa eastern jet,which act as the warm cover and the clod pad,provide energetic motivation condition for the heavy snowfall.Favorable upper and lower pumping configuration of divergence is weighted towards the long-duration snowfall.The snowfall is intensified by the riming effect.The snow center corresponds quite well to the concentrated belt of pseudo-equivalent temperature.The thunderstorm that occurrs in cold situation is a typical elevated thunderstorm in this case.The further diagnostic analysis of saturated moist potential vorticity shows that the thunderstorm occurrs in the conditional symmetric instability situation.The isentropic analysis reveals the trigger mechanism of the thunderstorm:The warm airflow climbs along the cold front from low layer to 600-650 hPa and meets the cold air,which triggers the thunderstorm.