Abstract: Using intensive and conventional meteorological data, geostationary satellite infrared cloud image and Doppler weather radar monitoring products, precipitation features, environment conditions, water vapor transport, energy field, evolution characteristics of mesoscale cloud, horizontal and vertical distribution of radar reflectivity during a heavy rain event on August 19 to 22, 2010 in Liaoning province were analyzed.The results indicate that there are two rainfall stages in this period, i.e.cold vortex moving east and low vortex moving north.In general, the heavy rain is characterized with large amount precipitation, long duration, wide range and strong local outbreak.Westerly long wave trough is stable.Subtropical high and Japan Sea high are maintained, so the situation of "east low and west resistance" is obvious.The upper and lower systems are coupled, including northeast cold vortex, high-level divergence, wind shear in the lower troposphere, low level jet and surface cyclone and so on.The dry cold air from the north and warm humid air from the south converge over the torrential rain region, and vapor conditions for the severe rain is favorable.With the cold frontal moving eastward, lifting conditions grows by the energy front.Many small-scale and mesoscale convective clusters develop into mesoscale convective complex (MCC).Areas of cold cloud anvil could decide ranges of precipitation.Directions of the echo long axis and echo movement are parallel, thus "train effect" is seen on the radar echo imagery during this precipitation period and leads to local strong precipitation.Meanwhile, radar echo has the characteristics of backward propagation and low centroid which is similar to the tropical heavy rainfall.

Key words: Severe precipitation, Northeast cold vortex, Energy front, Mesoscale Convective Complex (MCC)