Abstract:

 Based on data from conventional and automatic weather stations, satellite and radar, and the NCEP reanalysis data (1°×1°, 6 h), the mesoscale convective conditions and convective system characteristics of an extraordinary rainstorm process on August 15-16, 2013 at Heishan of Liaoning province were analyzed. The results show that the severe precipitation process is caused by mesoscale-β convectional systems. The short-term torrential rain area occurs at the edge of energy tongue. Surface eastward wind and topographic force are dominant factors that causes generation, development and movement of convection cells along the east side of mountain, which lead to the continuous and convectional precipitation. The mesoscale wind shear and vortex motivated by the northeast low-pressure cold front trigger the local torrential rain. Two separate convective cells generate in upper reaches of heavy rain areas, and merge together and then influence Heishan County. The oblique ascension airflow in front of echo moving direction and low heart echo both enhance precipitation efficiency.

Key words: High energy tongue, Mesoscale vortex, Terrain force, oblique ascension airflow