Weather radars provide high resolution in space and time and thus deliver distributed rainfall information. They therefore have high potential for exploitation in real-time flood forecasting. However, several aspects limit the accuracy of such data in flood forecasting systems. A major aspect is associated with the error included in the radar data and the limited lead-time. In order to assess real-time flood forecasts and improve their reliable lead times with radar rainfall data, this paper presents a framework for a radar-based flood forecasting model integrating radar rainfall data, geographical information systems, the hydrological model HEC-HMS and a short-term precipitation nowcasting system. The benefit of the radar-based flood forecast is analysed and the limits of predictability due to the meteorological aspects of the rainfall forecast as well as the hydrological model are investigated. The incorporation of the radar-based rainfall forecast demonstrates a strong potential for successful hydrological modelling and prediction.