Abstract:The fully elastic three-dimensional convective stormmodel(IAP-CSM3D)developed by the Institute of Atmospheric Physics(IAP),was used to simulate the strong convective storm occurred in Hunan Province on April 23,2004.A squall line swept over themost of Hunan Province,and the torrential rain(three-hour precipitationmore than 50mm)occurred in Shaoyang,Loudi,Changsha and Liuyang from 08:15 to 11:42 BST.Meanwhile hailstones attacked Changsha and Zhuzhou from 12:37 to 14:25BST.The distribution and evolution of themacro-physical as well asmicro-physical quantities of the strong convection process,such as wind field structure,radar echo,water content,etc.are simulated,and the formationmechanism of hailstones in the storm is analyzed.The simulation results indicate that the auto-conversion of frozen drops and graupels(CNfh,CNgh)are themain sources of the hailstones in the strong convective storm studied,but the contribution of frozen drops(CNfh)is greater than that of graupels(CNgh).The growth of hailstonesmainly depends on collecting supercooled water(CLch,CLrh).The Doppler weather radar observations are compared with the simulated airflow structure,and results indicate that the change of divergence with height observed is consistent with the airflow structure simulated,and that the reflectivity and echo top output from themodel are close to those observed.