A thunderstorm ensemble forecasting approach is performed by the ensemble analysis of the cloud model’s forecast results according to the initial condition aggregation provided by the grid forecast results of the mesoscale non-hydrostatic WRF model.The approach is applied to forecast the characteristics of thunderstorm around Nanjing one day in advance and is verified by the Doppler radar data of the thunderstorms in summer in Nanjing.Results show that the intensity and distribution of thunderstorms over the research area is reasonably predicted one day in advance.It is particularly good to forecast the distribution of the strong thunderstorms by using the ensemble forecasting technique.Moreover,the application of the PDF(probability density function)of thunderstorms’ duration into the probability forecasting of the influenced area of thunderstorms improves the radar’s warning and monitoring capacity of local thunderstorms.