Abstract:Based on the latest 10-year precipitation data, the relationship between the rainstorm areas, frequency etc. from April to September in Anhui Province and the 5840gpm isoline is statistically analyzed. And the comparisons between 20 rainstorm areas and some real-time physical variables during the flood season of the Huaihe River in 2003 are made. It shows that the rainstorm in Anhui Province mainly appears in the period from Meiyu season to July, and both the rain day number and the range of rainstorm basically determine the precipitation amount in flood season and the tendency of flood/drought. The rainstorm areas are concentrated on the 500hPa slope ranging from 5820gpm to 5840gpm while there is seldom rainstorm in the ranges less than 5750gpm and more than 5870gpm. Therefore, the prediction of main rainfall belts during the Meiyu season can refer to the movement of 5840gpm isoline. As to the physical variables, the regions in the north flank of westerly jet and those from the south flank of 500hPa ascending center to the north flank of 850hPa ascending center are favorable for the occurrence and development of rainstorm, whereas the stability in the mid-low troposphere and the 500hPa divergence have no close relationship with rainstorm areas.