Abstract: The formation causes of convection rainstorm weather in Wuwei City from afternoon to night on July 29, 2012 were systematically analyzed using the conventional weather charts, FY-2D satellite images and meteorological data observed by a meteorological station, and physical quantity field data. The result showed that the rainstorm occurred under the interaction of multiple factors and a certain largescale circulation background. Dramatic change of surface meteorological factors was an energy release process of strong convection weather. Local high humidity and water vapor convergence provided an abundant water vapor source for the rainstorm. Highlevel divergence, lowlevel convergence and strong ascending motion were the dynamic conditions of the rainstorm. Strong unstable energy and unstable stratification were the necessary conditions of enhancing the convection and increasing the rainstorm intensity. Development and strengthening of convective cloud clusters were the direct causes of the rainstorm intensity.

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