MESOSCALE ANALYSIS OF YUNNAN SUCCESSIVE HEAVY PRECIPITATION AROUSED BY THE STORM OVER THE BAY IN EARLY SUMMER

By using regular meteorological data, physical quantity fields, satellite pictures and Doppler radarecho data, we analyze the mesoscale features and the conditions of 4 successive heavy precipitation processes inYunnan aroused by the storm over the Bay in the early summer. The results show that the life of the storm overthe Bay is usual 2 or 3 days and the cloud top temperature of the storm is always below -65°C. The storm overthe Bay affects Yunnan by mesoscale convective cloud clusters, cloud system in peripheral or weaken itselfmoving to the northeast. The Tibetan Plateau shear lines and vortexes, NE-SW convergence channels andsouthwest wind convergence supply favorable circulation background and dynamical conditions. There are manycommon features about Doppler radar echoes, the flocculent echoes with intensity about 35-45 dBZ move to theeast to produce successive precipitation in Yunnan, and the mesoscale features of southwest jet and wind veeringwith altitude not only are favorable to transport warm and moist airflow brought to the north by the storm overthe Bay, but also are favorable to convective development.