By dint of V-3θ diagram from the Blown-up theory,a continuous heavy rain process in western Sichuan basin from July 14 to 17,2009 is analyzed in this paper.Situation field and precipitation of ECWMF and T213 are verified and discussed.Results show that V-3θ diagram can describe the heavy rain process accurately.Combining with additional conventional weather charts,experience and numerical forecast products,the heavy rain falling area is determined.The forecast accuracy of situation field of EC is significan...