Mesoscale Characteristic Analyses on Severe Convective Weather Process at Yuxi in Yunnan

By using routine sounding data,NCEP/NCAR reanalysis data,automatic weather station observation data and T639 numerical model forecast data,a strong convection weather process occurred in Yuxi in 9-10 June 2013 is diagnosed.The results show that this strong convection weather process was caused by the interaction of the warm-wet flow coming from southwest and the cold air from north guided by the northwest flow behind trough,occurred in the north of the middle Yunnan Province.The direct impact systems of this process are shear line in the lower troposphere,surface mesoscale convergence line and the cyclone type convergence center.Convergence of the water vapor from the Bay of Bengal in Yunnan attributes favorable vapour condition to this process.Analysis shows that there is a good corresponding relationship in the mesoscale severe convective cloud band,surface mesoscale convergence system and the discontinuous band of the convective available potential energy(CAPE).The location where the mesoscale convective band generate and develop is essentially consistent with the surface convergence line which formed early.The convective cell is more easily to get strengthened and developed on the large value area of the discontinuous band of CAPE.Thus the comprehensive analysis of surface flow field and high-resolution distribution of CAPE have a certain indicative significance to the short-term weather forecast of the severe convective weather.