Abstract:The evolution characteristics of radar echo and environmental parameters of the severe convective storm in central Yunnan on 23 August 2017 are analyzed using conventional observation data, automatic weather station data, Doppler radar data, NCEP (1°×1°) 6 h reanalysis data. The main conclusions are as follows. This severe convective storm occurred under the background of strong unstable conditions caused by the front side of typhoon depression system moving westward and the rear side of mid and high latitude cold trough. Surface convergence lines and strong vertical wind shear were conducive to the maintenance and enhancement of convective storms. The severe convective storms were influenced significantly by the topography and six supercells or similar supercells were induced during the evolution of convective storms. The strong centers of three hail supercells climbed along the terrain, while the non-hail and small hail supercells descended along the terrain 10 minutes before the supercells developed to maturity. The six supercells or similar supercells had characteristics of mesocyclone or meso-γ scale vortex. Hails occurred when the maximum velocity to rotation value in the supercell exceeded 10 m·s-1. The velocity at elevation 2.4°-3.4° reached the mesocyclone standard when the diameter of hails was bigger than 15 mm. There were the characteristics of higher reflectivity centroid point, echo nuclear tilting forward, weak echo zone, the echo wall and three-body scatter for supercells with 15-20 mm hail particles. In addition, the radial velocity showed the following characteristics. The zero velocity line tilted back, the height of the convergence zone exceeded -10℃ layers of supercooled water zone, a strong divergence zone appeared at the top, the maximum echo intensity of the -20-0℃ layer exceeded 55 dBz, the thickness of the 50 dBz echo was more than 6 km, and the density of vertically accumulated liquid water content (VIL) was larger than 2.2 g·m-3. The echo nuclear shows an upright shape, the characteristics of overhanging echoes were not significant, the height of the convergence zone was low and the thickness of the divergence zone was higher than that of the convergence zone, for supercells of non-hail and 5-8 mm small hail particles. The maximum echo intensity of different isothermal layers showed little difference, but the 50 dBz echo thickness was less than 6 km, and the VIL density was less than 2.2 g·m-3.