The combined effects of typhoon Fitow and Danas together with cool air on an excessive heavy rainfrom October 7 to 8 in 2013 in Shanghai

Based on routine weather maps, FY-2E satellite cloud images, wind profiler radar data, reanalysis data from NCEP and operationalnumerical forecast data, we have analyzed the effects of typhoon FITOW (1323) and DANAS (1324) together with cool air on an excessiveheavy rain event occurred in Shanghai from October 7 to 8 in 2013. The results show that the plentiful supply of water vapor and energy requiredfor the event comes from the low pressure circulation with typhoon FITOW that is weaken after its making landfall and the strong easterlyjet in the north side of typhoon DANAS. The meeting of cold air spreading from north to south, low pressure circulation with typhoon andstrong easterly jet mentioned above strengthens the upward motion induced by convergence. Analysis of wind-profile radar data found thatshear line in the low-level continued for a long time over Shanghai, which is the main reason that leads to an excessive heavy rain event inthis region. In the satellite cloud images near the shear line that lasted for a long time, it can be found that 5 meso-β scale convective cloudclusters successively originated and merged, and hence cause the severe precipitation continuing. Forecast verification of different numericalprediction models indicates that there are remarkable forecast errors in distribution, intensity and time interval of rain among these numericalprediction products because they cannot accurately predict location, intensity and structure of typhoons. In order to reduce forecast errors frommodels, we should devote much attention to the application of real time observations, particularly the use of wind profile radar network data forshort term early warning of extra heavy rain.