Abstract:Based on the conventional sounding observation data, Doppler radar data and wind profiling radar data, a thunderstorm gale process that occurred in Hunan and Guangdong from the night of 19 to the morning of 20 March 2013 is analyzed. The results show that the background of this strong convective weather process is the collapse of the northern branch ridge and the establishment of the southern branch trough. Strong low level jet and the shear line appear before the trough, which causes the dry and cold air above the level of the warm and humid air and makes the convection develop strongly. The automatic observation shows that the convective cell is triggered when the north wind enters into Huangping Guizhou (where the dew point temperature is higher than the surrounding areas) and forms wind convergence. After that, the convective cells moves into the south region of Hunan where there is a convergence line matching a dew point front and strengthens to a severe convective zone while it is extremely cold and dry at 500 hPa. Over the night of the 19th many convective cells emerge in the western Hunan, forming a squal line at last. There are many supercells in the squal line. By comparing the mesocyclone product of the radar with the time of the thunderstorm gale, it is found that the bottom of the mesocyclones continues droping to below 2 km about 2-3 volume scans before the appearance of the most thunderstorm winds resulting from the mesocyclone, and the strongest shear height drops to the bottom height of mesocyclone about 1-2 volume scans before the appearance of the thunderstorm gale. In addition, after comparing the wind profiler radar data with the time of thunderstorm gale, we also get conclusion that a substantial jump of the bottom refraction index structure constant (C2n) always appears about 10-15 min before the time of thunderstorm wind, which is probably indicative to the appearance of wind.