“…That is, it represents the fact that, for τ values lower than basin lag time (L), with a well-calibrated hydrological model, and forecast updating in real-time, the performance of a forecasting model is relatively high as forecasts are based on observed precipitation by using, for example, gauge-based quantitative precipitation estimation (QPE). Past this value L, the forecasting model has to be forced with quantitative precipitation forecasts (QPFs), and forecasting performance is assumed to drop monotonically (Schröter et al, 2008). The slope of this function for a lead-time less than L defines the quality of forecasting models based on gauge-based QPE or gauge-radarbased QPE, and the slope beyond L defines the quality of the forecasts based on QPFs.…”