Analysis on Causes of the Continuous Heavy Rain in 2003 in Shaanxi

The analysis of causes the continuous heavy rain in 2003 in Shaanxi shows that the collocation of the blocking high of Ural and subtropical high, and their stabilization provide favorable background to the continuous heavy rain. The main cause of the continuous heavy rain formation is that the cold air, which leading by the small trough splitting from the bottom of Baikal low, and warm-humid airflow from the west (northwest ) side of subtropical high that mixed time after time on east side region of Plateau. The coupling of high-low jet induces high divergence area overlaying on the top of low convergence area, consequently leading intense ascending movement. It provides the condition of deep convection development and promotes the formation and maintenance of mesoscale system when heavy rain occurs.