Analysis on mesoscale characteristics of a severe convective storm event in western Chongqing on 23 July 2011

Based on data from conventional observations, intensive network of automatic weather stations (AWS), ADTD lightning instrument and weather radar, we analyzed the mesoscale characteristics of a severe convective storm event occurred in western Chongqing on 23 July 2011. The main results are as follows. (1) The event occurred under the condition of a cold low circulation between the Tibet high and the subtropical high. Several factors such as strong unstable stratification, sufficient water vapor in the low level, large downdraft convective available potential energy (DCAPE) and moderate vertical shear in 0-6 km are favorable to the development of the storm. (2) The disastrous gale ismainly located in the center and its surrounding areas of surface heavy rainfall and high density of ground lightning. Mesoscale characteristics associated with the ground gale, such as convergence line, convergence zone, cold pool and thunder high, are observed by AWS. Negativecloud-to-ground (CG) lightening dominated in the event, and the ratio of negative to positive CG is approximately 101:1. (3) The gust fronts,echo hanging, weak echo region (WER) and boundary weak echo region (BWER) are quite clear on the PPI and RHI charts of radar reflectivityfactors, and features such as mesosyclone, divergence on low tilts, large radial velocity region, inflow flows, divergence in the upper level and convergence in the low level are also evident in the radial velocity chart. The above characteristics are of significant importance in disastrous gale detection and its early warning.