Two Heavy Rain Process Analysis and Forecast in July 2009 in Guilin

Two heavy rain process weather situation,physical mechanism and radar echo characteristics were analyzed by means of conventional sounding records,numerical forecast products and radar echo data from July 2 to 4,25 to 28 in 2009 in Guilin,Guangxi province,the results showed that low vortex shear were the main effect system to two heavy precipitations and there was a direct relationship between south-west low-level jet and the order of rainstorm magnitude,strong convergence and upward motion formed in the configuration of low vortex shear and south-west low-level jet were the dynamical mechanism in two heavy rain,the stronger the convergence and upward motion,the greater the corresponding rainfall intensity;it was relative between the stability of floccus echo of heavy precipitation over in Guilin and its the strong south-west warm air convergence in its internal wind structure,and the round floccus echo was more stable than the long strip ones,the more conducive to the formation of heavy rain.In addition,the practice had proved that the use of a variety of numerical forecast products and local forecast tools and indexes can make quite accurate forecasts to rainstorm area and magnitude,which can provide an effective weather forecasting and decision-making services.