关键词: 局地强降水, 中小尺度系统, 中气旋

Abstract: Based on the Doppler radar products and T639 reanalysis data, small-scale system characteristics of a rare heavy rain on June 22, 2010 in the south of Shihezi and its occurrence time and falling area were analyzed. The results show that mesoscale short wave split from cold low-pressure from Siberia to Lake Balkhash is the direct influencing system of this process. The middle scale shear line from low level to ground and convergence line as well as cold front are the trigger mechanism for the local heavy rain. There is the transportation of strong southwest and southeast warm-wet air flow and their strong convergence in front of the mountain near low level, which provides the effective moisture and unstable energy for this process. Multiple-γ convective cells roll and change along the special topography, which are the direct reasons forming falling areas of the local strong rain event. The occurrence of meso-cyclone is indicative to the heavy rain. The heavy precipitation occurs in the superposition areas where the echo intensity is more than 50 dBz, the echo top height exceeds 5 km, vertical accumulated liquid water content is above 45 kg·m^-2 and it exists in the mesocyclone. It is in advance about 20 min for warning of short-time strong precipitation using mesocyclone.

Key words: Local heavy precipitation, Meso-small scale system, Mesocyclone