Abstract
By using the data of automatic weather stations，satellite images，sounding，etc.，the short-term strong rainfall weather process were analyzed which cause a large debris flow at Zhouqu of Gansu Province on Aug. 8, 2010. The results showed that meteorological elements of the automatic station changes can reflect the small and medium scale weather system．A tail of frontal cloud into the east of South Asia high stimulates the convective clouds， the humid conditions，unstable stratification and the larger upper wind vertical shear，made cloud cluster in rapid development and merge into the MαCS，in the direction of the right rear edge temperature gradient of the place appear short-term strong precipitation. The edge of the subtropical high vapour conveyor belt make south Gansu have convection development potential，500 hPa small groove，200 hPa divergence，ground front，stimulate mesoscale convective system ( MCS) ，make it to development．Favorable stratification conditions and high altitude wind vertical shear make MCS to strengthen，resulting short local strong rainfall at Zhouqu，and trigger large flash flood debris flow．
