Using the U.S.National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data at 1°× 1° resolution,analysis is performed on a persistent heavy rainfall event with two rain bands to the south of the Yangtze River during 17-22 June 2005.The northern rain band was related to the atmospheric mass adjustment of cold front precipitation and the associated ageostrophic feature to the rear right of subtropical westerly jets,while the southern counterpart formed under the joint influence of easterly/westerly jets and the South Asian high(SAH).The ageostrophic wind field to the rear right of the easterly jet center gives rise to an anti-circulation that favors the genesis of the southern belt.The feature of du/dt