Synthetic Analysis of a Strong Squall Line in Eastern Henan

A synthetic analysis on the circulation patterns,influence systems and formation mechanisms of a strong squall occurred in eastern part of Henan province on 3 June 2009 was made with the 6-hourly NCEP 1°×1°reanalysis data,conventional observation data,intensive automatic weather station observation data,satellite images and Doppler-radar data.The results indicate that the Northeast China cold vortex continuing,the zonal trough behind the cold vortex leading cold air to a southward move and the surface mesoscale convergence line supplied a trigger effect for the occurrence of strong squall.The squall developed and reinforced along convergence line,and severe convective weather emerged in the great value center of brightness temperature gradient of satellite images.The changes of the squall line process corresponded to the genesis,developing,merging and weakening of severe convection cells which could be found in the radar echoes.The back of convergence line on the storm radial velocity plot was all the way corresponding with gale,hail and other strong convective weathers,which can provide better indications for severe convective weather forecast.