721-Beijing Rainstorm Process Analysis Caused By the Hetao Cyclone Development Eastward Shift

This paper diagnostic analysis the 721-Beijing rainstorm weather process caused by the Hetao cyclone development eastward shift，the results show that: Hetao cyclone is the major affected system of 721-Beijing rainstorm weather process，the 700 hPa strong cold air activities blocking the Hetao cyclone northward conventional path，forcing its eastward shift and directly affect the Hebei and Beijing. In the process of Hetao cyclones eastward shift，the warm heart barotropic cyclones change into baroclinic cyclone and strong development, its vapor, heat and High-low level jet stream coupling conditions significantly strengthened with the Hetao cyclone eastward shift ,is the main reason of the precipitation increasing from west to east. Afternoon, warm front triggers the release of potential instability energy with the Hetao cyclones eastward shift, generated strong convective system, formed mesoscale convective complexs (mcc) in the Beijing area, make precipitation further strengthen, is the main reason of 721-Beijing rainstorm. The topographic Lifting increase the role of the precipitation in the southeast airflow, 721-Beijing rainstorm is caused by a variety of favorable factors superimposed.