Aims, challenges and progress of the Hydrological Ensemble Prediction Experiment (HEPEX) following the third HEPEX workshop held in Stresa 27 to 29 June 2007

Abstract Since several years, users of weather forecasts have begun to realize the benefit of quantifying the uncertainty associated with forecasts rather than relying on single value forecasts. At the same time, hydrologists and water managers have begun to explore the potential benefit of ensemble prediction systems (EPS) for hydrological applications. The Hydrologic Ensemble Prediction Experiment (HEPEX) is an international project that aims to foster the development of probabilistic hydrological forecasting and corresponding decision making tools. Since 2004, HEPEX has provided discussion opportunities for hydrological and meteorological scientists involved in the development, testing, and operational management of forecasting systems, and end users. Copyright © 2008 Royal Meteorological Society