Abstract:Based on the Doppler weather radar data of Liuzhou and Guilin, and the conventional upper air and surface observation data, this paper analyzes the environmental condition and radar echo structure of the severe hailstorm which occurred in Liuzhou on 9 April 2016. The results show that: (1) The background responsible for the hailstorm includes intense heating up of the surface which led to the development of thermal depression in the lower atmosphere, the developing eastward cold temperature trough in the mid level, and an upper level jet stream above the convective location. The convective clouds triggered by surface dryline and the mesoscale convergence line evolved into supercells under the influence of the unstable stratification and significant vertical wind shear. (2) The low level reflectivity of the supercell showed a typical hook echo or inverted V notch. Along the inflow direction and through the strongest echo, the reflectivity showed typical BWER, overhanging echo and echo wall. The strongest echo was within a vertical narrow zone along the echo wall and the value got to 65 dBz. The corresponding radial velocity in the lower atmosphere had a strong mesocyclone with rotation speed reaching 24 m·s-1. The development and maintenance of mesocyclone made the supercell storm develop and maintain. (3) Maximum reflectivity reaches 60 dBz, strong echo over 50 dBz extending to the height of -30℃ layer, VIL value over 60 kg·m-2 and VIL density over 5.0 g·m-3, mesocyclone in moderate or severe intensity can be taken as the early warning indicator of severe hail.