Comparative analysis on two severe convective weather events occurred near the subtropical high ridge in Jiangsu Province

Using conventional observation data, automatic weather station (AWS) data, Doppler weather radar data and FY-2D & FY-2E satellite cloud images, comparative analysis is conducted for two severe convective weather events near the subtropical high ridge in Jiangsu on 18 and 23 August 2010. The results indicate that (1) when there is sufficiently strong lifting mechanism, severe convective weather will be triggered in the vicinity of the 500 hPa subtropical high ridge line, and it is situated near the surface convergence line and 925 hPa shear line. (2) Atmospheric stratification is unstable before two severe convections are triggered, the lower levels are wet and the upper levels are dry. These two events indicate that the thunderstorm wind corresponds to a dry atmosphere in the middle and upper levels. The short-time heavy rainfall corresponds to thick wet layers in the lower atmosphere. (3) The convective storm is triggered by the surface strong dynamic lifting on 18 August. On 23 August, the level of free convection and convective condensation level are low, convection temperature also is low, and there is no convective inhibitory energy. Finally, the boundary layer dynamic lifting and the ground thermal lifting are combined together to trigger the convective storm. (4) The time of the appearance of low-altitude convergence in the radar radial velocity map of Doppler weather radar is earlier than the convective cell generation. The low-altitude convergence is gradually sustained or enhanced with time, which is in favor of the rebirth and development of local convections, which has reference significance for forecasting and warning.