关键词: 持续性致洪暴雨, 低空急流, 大气不稳定, ＭＣＣ

Abstract:

By using the observational data，satellite product and NCEP reanalysis data，the two convective rainstorm weather processes in central and southern areas of Guizhou from May 25 to 27，2008 and from June 4 to 5，2011 were analyzed．The results show that under the relatively stable circulation situation on 500 hPa，there were small trough moving eastward continuously over the Qinghai － Xizang plateau with low vortex shear at the middle and low level，which resulted in the two torrential rain processes，and two rainstorm processes were caused by MCC in Guizhou． During the first weather process ( May 25 to 27，2008) ，the atmospheric stratification was extremely unstable，and the upward movement was very strong，but during the second process ( June 4 to 5， 2011) ，there was stationary front maintaining in the central line on the ground in Guizhou，the atmospheric was neutral or stable stratification，but low － level jet condition was better than that of the first process．There were some differences in moisture condition，instability condition and uplift mechanism during two rainstorm processes，which associated with the location of the subtropical high． The mesoscale low pressure convergence line or the stationary front existed on the ground，which strengthened convergence movement and resulted in mesoscale convective complex generation in the south region of Guizhou Province． Based on the analysis results，this kind of rainstorm forecast index was discussed in this paper．

Key words: rainstorm, low level jet, atmospheric instability, MCC