Abstract:Based on observation data of automatic weather station, conventional observation data, NCEP reanalysis data and the forecast products of two models, the cause of formation and prediction of local extreme short-term heavy rainfall on 7 July 2016 and stability extreme rainfall on 22 April 2018 in Yichang Gorge were analyzed. Results show that:(1) the strong block echo is stable and less dynamic, which results in high efficiency convective precipitation on July 7. The convective precipitation increases obviously due to the forced uplift of topography, and the echo of front stratiform cloud is affected by terrain blocking, and the long-term maintenance is the main reason for the formation of stable extreme precipitation. (2) The main reason for the formation of extreme short-term heavy rainfall is that the valley wind forms mesoscale shear line, the mesoscale shear line stimulates convection, and the mesoscale shear line developes into mesoscale vortex to strengthen convection.(3) The intensity of convective precipitation increases obviously due to the forced uplift of topography, and the echo of frontal stratiform cloud is affected by terrain blocking and the long-term maintenance is the main reason for the formation of stable extreme precipitation. (4) The performance of regional models with large terrain difference is quite different, and the prediction of convective precipitation under complex terrain is weak, which leads to the difference of system intensity, and then affectes the prediction of precipitation intensity.