Weather Analysis of a Continuous Rainstorm in Wenchuan Earthquake Center

Based on the NCEP /NCAR 1°×1°reanalysis data,air sounding data and surface data,the formation mechanism of continuity storm in Northern Sichuan Plateau are studied.Result show that this process occurs in subtropical westward extension to Tibet Plateau and shaped a strong high pressure zone.After the high pressure zone is ruptured,it formed long time shear between the two high pressures and it slowly moved eastwards to trigger release of unstable energy.The southwest low level jet transports water vapor for the rainfall areas on 700hPa.Surface cold front slowly moved eastward by the subtropical high blocking.