The Analysis on the Radar Characteristics of the Local Heavy Rainfall on 20050902 in Lunan

Using the comprehensive information of Jinan radar echoes and automatic weather observation networks,an extreme precipitation event at Guolou town,Jining city on Sep 2nd 2005(20050902) is analyzed. The synoptic analysis of the event data shows that the rainstorm happened in a southward withdrawal process of the west Pacific subtropical high,when the atmospheric temperature stratification was strongly convectively unstable. The convective echo band producing the torrential rain was vertically in a convergent area at low level in the conjunction of a divergent area aloft,and its location coincided with an shear line at low level; and in the narrow and persistently strong convective echo band,strong echoes with features of Meso-γcyclonic rotation persistent for four hours above Guolou town,enhanced the precipitation intensity of the rainstorm in this area.