On adapting PQPFs to fit hydrological needs: the case of flash flood forecasting

A simple, but rather complete hydro-meteorological system for ensemble flash flood forecasting is described. Special focus is put on the use of precipitation forecasts, essentially quantitative and overall probabilistic (PQPFs). A first issue addressed concerns the matching of the time-step used by the meteorological forecasts providers (12 or 24 h) with the appropriate hydrological time-step for quick responding catchments (1 h or less). A second issue concerns the forecasts management between two updating cycles of the PQPFs. Finally, ensemble discharge forecasts for a case-study event observed in Vogüé (South-eastern France) are illustrated as an application of our flood forecasting system.