Analysis on the Cause of a Rainstorm Forecast Deviation

By using conventional meteorological data,the analysis on the cause of the intensity differences during rainstorm process in Tai'an areas on July 20,2010 was carried out based on the weather situation,radar echo,satellite cloud image and numerical prediction.The results showed that the precipitation was caused by the joint action of southwest vortex,upper trough,shear line,subtropical high and low-level jet stream.The main reasons of the differences between the intensity and the actual situation were: the forecast grade of Japanese numerical prediction was smaller and the analysis of water vapour transport was insufficient.