The Analyses of a Spring Thunderstorm Weather Process in the Region of Zhejiang central of JinHua on the Mar 20th in 2013

In order to find out the development mechanism of severe convection in spring,with conventional observation data,MICAPS data,and a new generation doppler weather radar data,a wide range of severe convection weather,happened in the morning on March 20,2013 in Jinhua,was analyzed by synoptic and dynamical methods which.The results show that:(1)The main influencing system is upper trough and ground inverted trough;(2)The water vapor transport is strong in the process,because three high-layers are all controlled by southwest jet;(3)The dynamic condition is ideal,for there are severe vertical ascending motion centers almost overlapping near the jet and the vertical wind shear is strong from 500 hPa to the ground;(4)The interaction between strong warm advection in low-levels and weak cold advection in high-level leads to the unstable stratification with warm-wet air under dry-cold air;(5)Cold air infiltering from middle-level prompts the further development of strong convection,the storm develops into a meso-scale squall line without any gust front;(6)The supercell storm in the south of squall line develops into a non-supercell storm with the feature as″bow″echo in radar product,and the top of the echo brings instantaneous wind of 27.4m/s when it passes Wuyi;(7)VIL high value maintains in shot time that hail can hardly occur.