Precipitaion Forecast and Numerical Experiments on "200.10.18" Rianstorm Process by Using a η Model

Adopting the methods of numerical simulation and weather analysis, and according to circulation background and main affecting system of the occurring rainstorm area on October 18 to 20, 2002, numerical experiment and contrast analysis of precipitation forecast have been done by a η coordinate model. The results show that the ηmodel has a better performance in the forecast of heavy rainstorm. Under the favorable circulation background of precipitation, the high temperature in the basin and cold air activities near the ground are the keys to the storm rainfall occurrence. The more(less) rainfall is greatly depended on the strong(weak) intensity of the converge of cold and warm air. The existent in upper air jet stream is available for the increasing in precipitation.