Based on a variety of densely observed data from automatic surface weather observation system, NCEP/GFS 0.5°×0.5° analysis data, the temperature of black bold (TBB) observed by FY2E satellite, the evolution of the heavy rainstorm process in Hubei Province during 5-6 July 2013 is analyzed. Using the highresolution output from WRF model, the evolution of the mesoβ scale systems is diagnosed. The results show that the severe convection took place in the overlay zone of positive vorticity in front of trough at 500 hPa, the shear line of low layer near jet flow nucleus, the upper divergence and the instability energy. There were three mesoβ scale systems in the largescale favorable weather situations, and the heavy rainfall groups were associated with the development of the convective systems. Considering the coalescence growth of droplets of the saturated water vapor, cloud water and cloud ice, the WRF model diagnosis is discussed through the precipitation rate of flux divergences. We have found four mesoγ scale systems in rainbands from the evening of 5 July to the morning of 6 July 2013, and the physical quantity value could quantitatively estimate the hourly rainfall intensity to some extent. Maximum probable convective precipitation rate could be a better physical quantity value to reflect the relations of the vapor condition in mesoscale rain cluster, thermodynamic condition and rainfall. Thus, it could be applied to the Doppler weather radar nowcasting.