Analysis of Satellite Cloud Image and Radar Echo Features of a Strong Squall Line Weather

By using the routine observational data,automatic meteorological station data,satellite cloud images and Doppler radar data,the squall line weather process occurred on May 30,2005 in Shaanxi province was analyzed.Results show that the influence systems from surface to 500 hPa level presented slanting forward structure,which made the atmospheric instability under the control area suddenly enhance,and with the Mongolia cold cyclone rotation and cold air thrown from its tail,the meso-β scale convective system(MβCSs)was formed,and all those supplied the prophase dynamic and thermodynamic conditions for the squall line weather.Analysis of surface stream and energy fields obviously showed that the squall line occurred behind the surface shear line,and before the convergence area of wind.The Doppler radar data analysis showed that the squall line echo presented linear distribution and developing rapidly,moreover the maximums of composite reflectivity and radial velocity went with the squall line for a long time.When the squall line cell echo entereddead wind area,it developed more rapidly, which resulted in not only gale and hail but also shortly rainstorm.