Cause Analysis of a Heavy Rainstorm Process in Tongren City in Autumn,2012

By using conventional observation data,ground encryption automatic stations,NCEP1 ° × 1 ° grid points reanalysis data,main influencing system and characteristics of physical quantity field of the heavy storm in Tongren City during October 21- 22,2012 were analyzed. The precipitation forecasting was tested based on WRF model. The results showed that: the main cause of the heavy rain are the system 500 hPa low slot,700 hPa shear,850 hPa vortex shear and surface cold front; the rainstorm formation,strengthen and weaken are closely related to the evolution of the heavy rain over the water vapor flux convergence zone. Low-level convergence,high-level divergence the vertical dynamic field structure,so that the entire layer organized upward motion,provided the impetus for the occurrence of heavy rain conditions; the lower troposphere θse with reduced height,reflecting the lower atmosphere during the storm not stability,and the middle atmosphere in the neutral atmospheric stratification is conducive to produce strong convective precipitation; WRF mode precipitation forecast for the heavy precipitation has important significance,compared to nearly 24 hours of the precipitation area and the fact consistent better,but the precipitation level forecast is slightly smaller,heavy precipitation forecast period,compared with the fact of earlier six hours,which needs to integrate the development of the situation of other numerical forecasts revised forecasts.