Analysis on a Heavy Rain Process in a Warm Sector in Guangxi in June 2008

Circulation characteristics and influencing systems of a continuous rainstorm in a warm sector between June 8 th -13 th 2008 in Guangxi are studied by using the routine observational data,TBB and NCEP re-analysis data,.Results show that this rainstorm process was formed under a circulation adjustment at 200hPa and a weak block high over Baikal Lake-Xinjiang and a frontal trough at ground.The weather system included a low-1evel shear line and a low vortex.The wind speed convergence at low level strengthened by establishment of jet stream rapidly was the favorable factor of heavy rain happening in warm sector ahead of the front.There were a significant difference on the structure of vertical movement in the shear line and low shear vortex.The convergence on the lower level and strong divergence at high level led to increasing movement more strongly in shear vortex than in the shear line.The relative humidity increased markedly before heavy rain so that the wet layer was very deep,and in high layer the relative humidity first to downward when precipitation decreased.The period and falling-area of heavy rain were corresponding with the center of water vapor flux.There was a monsoon surge in southern china bringing water vapor and energy from South China Sea for this continuous rainstorm process.