Weather radar measurements of rainfall are the alternative to traditional precipitation gauges networks used for estimation of spatial distribution of precipitation. Although the resolution of radar-based precipitation sum product (PAC) from Polish radar network (POLRAD) seems to be very promising as source of distributed input data for hydrological models there are also certain limitations which have to be taken into account. This paper presents an application of PAC radar product to hydrological forecasting with rainfall-runoff models and compares the results to traditional rain gauges based modeling.