The diagnostic analysis on a heavy precipitation supercell storm process in northern Jiangsu province on 22 July 2008 is implemented by using the conventional observation data,NCEP reanalysis data,FY2C satellite products and CINRAD-SA Doppler radar data.Weather analysis shows that the synoptic environment is characterized by the high humidity,strong convective instability(convective available potential energy,3 445 J/kg),medium to strong vertical wind shear (0-6 km,18 m/s) and low LCL (lifting condensation level),which directly result in the generation and development of the heavy precipitation supercell storm.The radar echo analysis shows that the evolution of the heavy precipitation supercell can be generalized into three stages:the isolated cell develops increasingly,evolves into a classic heavy precipitation supercell and then weakens eastward gradually,lasting more than 2 h.Doppler radar base reflectivity and storm-relative radial velocity observations on various elevation angles are used to investigate the radar echo features of the heavy precipitation supercell storm.The results show that at its mature stage,the heavy precipitation supercell storm displays a low-middle-level bounded weak echo,the larger radar reflectivity factor sloping toward the low-level inflow from low level to high level,and associated typical front inverted "V" notch echo with the inflow in middle and lower levels.Corresponding radar radial velocity images show that a well-developed mesoscale cyclone is in company with the inverted "V" notch echo in front of the supercell storm,and coincident with the heavy precipitation area at the surrounding of the inverted "V" notch echo.Through diagnosing the moist potential vorticity on isentropic surface and the moist potential vorticity during the process,results suggest that the intrusion of the durative dry cold air in upper levels touches off the release of potential convective instability energy,which is in favor of the development of convective motion.The atmospheric convective instability and conditional symmetric instability coexist in middle and low levels,so there are vertical convection and slantwise convection during the heavy rainfall,meanwhile the easterly inflow adjacent to the boundary layer transports ample water vapor to the heavy rain area,which plays an important role on the generation and development of the heavy rainstorm.