Observation Study on the Evolution Process of a Supercell Severe Hailstorm

doi:10.3969/j.issn.1673-7148.2012.02.001

Abstract：Based on FY- 2D/E satellite and TITAN radar observations, the evolution process of a supercell severe hailstorm occurred in Guangdong on 17 April 2011 was analyzed. The satellite cloud picture and surface monitoring data indicated that the cloud experienced four stages, which contained primary period, evolution period, maturation period and extinction life period. The cloud moved more than 600 km from primary to extinction, and lasted for more than 10 hours, which caused hail in six districts of Guangdong. In the maturation period, cloud kept isolated elliptic moving to the southeast direction. The coverage area was very great with over 300 km length and 100 km width, and the part Tbb is lower than -75 ℃. All these characteristics indicated that the cloud system was a typical supercell severe hailstorm. The radar echo pictures showed that, at mature stage （10：00--14：00）, the echo maintained the bow, which ruptured twice during the process, and a ＂V＂ shaped gap appeared in radar echo combination reflectivity maps. During the mature stage, a typical bounded weak echo region （vault） , strong echo trailer above it and echo wall on the left side of vault occurred. The velocity field showed that the convergence of east wind and west wind was the reason of vault maintains. These characteristics are typical features of supercell severe hailstorm. TITAN calculated hail index and storm attribute revealed that, this supercell had the hailshooting potential, and the probability of hailshooting （POH） reached 100% and lasted for 4 hours during 10：10--14：10, which have important denotative meaning on the shortterm forecasting and nowcasting of supercell storm and artificial hail suppression work.