Ensemble forecasting techniques have made significant progress in recent years and proved to be essential in hydrological prediction. Enhanced early warning systems and, in particular, coupled meteo-hydrological forecasting systems play a key role in increasing preparedness and reducing weather-related losses. The value of ensemble forecasting systems has been recognised across a wide range of sectors and users, including river basin authorities, public agencies, private entities and commercial industries. The growing use of ensemble and probabilistic products has shown the importance of avoiding misrepresentation and miscommunication of uncertainty to decision-makers. Interdisciplinary projects are thus crucial and can provide the basis for tracking uncertainty from atmospheric forcing to streamflow predictions.
This session aims to bring together scientists and practitioners from the fields of hydrology, hydrosystems engineering, meteorology and social sciences, as well as stakeholders and decision-makers, interested in exploring the use of ensemble forecast techniques in hydrological forecasting, reservoir operation and other water management regulations. General questions to discuss are:
- What is the contribution of the different sources of uncertainty involved in ensemble forecasting? Do we really need to take all of them into account?
- Is new science really improving weather-related disaster management and effective influencing policy-makers? If yes, how? If not, why not?
Contributions will cover but are not restricted to the following topics:
 Data requirements and data assimilation techniques to improve model initialisation and the predictability skill of hydro-meteorological ensemble forecasting systems;
 Methods to correct forecast biases (pre- and post-processing) and to assess or benchmark the performance of ensemble forecasts;
 Ensemble prediction studies carried out within different hydrological and climatic regimes;
 Methods and products for improving the human interpretation of forecasts (forecaster expertise) and for the efficient communication of ensemble predictions;
 Practical applications of operational or pre-operational ensemble systems: implementation of real-time procedures, users' needs and forecast products, post-event analyses and experience with the use of uncertain forecasts in risk-based decisions.
We encourage contributions that document successful experiences, as well as problems and failures encountered in the practice of operational ensemble hydrological forecasting. Contributions in the context of the international initiative HEPEX are also welcome.