Abstract: Based on the data from the conventional and intensive observations,satellite,radar,and the NCEP (National Centers for Environmental Prediction) re-analysis,the typhoons affected Ningbo,which landed in Fujian province but not in Zhejiang province,were investigated.The possible causes of heavy rainfall-induced by Typhoon Fitow,Dujuan,and Meranti in Ningbo were discussed.The results indicate that 43.9% of eighty-two typhoons selected from 1949 to 2016 results in local rainstorms in Ningbo,9.8% results in local large rainstorms,and 4.9% causes a city-wide large rainstorm.75% of these typhoons occur after 2013.It is found that after the weakening of a small scale typhoon coming from far-distance,the interactions of cloud diffusion with cold air,subtropical high and other typhoons facilitate to the formation of jet current and continuous heavy rain in Ningbo.However,the extension and degree of its influence are difficult to grasp.The increase or decrease of low-level water vapor supply is 6-12 hours ahead of the beginning time of rainfall increasing or decreasing.The strengthening or weakening of negative non-geostrophic wet Q-vector divergence may indicate the beginning or weakening of heavy rain with 6 hours in advance.

Key words: Typhoons, Heavy rainfall, Low-level jet, Non-geostrophic wet Q-vector