Synthetic Analysis of a Flood Heavyrain Event in Weihe Basin in 2003

In this paper,a heavy rain in Weihe basin on 28th august 2003 is studied by the synoptic meteorology and dynamical diagnosis analysis.The results show that the strong west Pacific subtropical high is beneficial to heavy rain to continue.The vortex and shear on 700 hPa level caused the heavy rain directly.There are the strong ascending motion and the structure with divergence on upper level and convergence on low level over the rainfall area to make the meso-scale secondary circulation in favor of the heavy rain maintaining.There are a strong energy front,convective instability and the classical Ω structure of θse in the rain area.The vapor is from the Bay of Bengal and the South China Sea.