GloFAS Sub-seasonal and Seasonal hydrological outlooks

The GloFAS long-range forecasting system has two flavours: the seasonal and the sub-seasonal outlooks. The two systems use different meteorological forcing in their model chain (for details see: EFAS meteorological forecasts) and are issued with different frequency. The seasonal forecast is issued monthly (for the 1st of each month), while the sub-seasonal is issued daily.

This page provides a detailed description of the meteorological forcings used in GloFAS.

Which products does GloFAS Seasonal offer?

GloFAS Seasonal offers a range of forecast products and associated information, accessible via different layer tabs of the GloFAS map viewer:

• Under the hydrological tab, maps of where a high/low flow signal is expected over the GloFAS river network or on specific catchments over the next 7 months for seasonal and 5-6 weeks for sub-seasonal
• Under the evaluation tab, maps of hydrological model performance and seasonal forecast skill

The forecasts provide hydrological outlooks which show the likelihood of different extent of high and low flows and the related uncertainty of the forecast. The temporal resolution of the forecast signal is calendar monthly, out to 7 months, for seasonal, and calendar weekly out to 5-6 weeks (depending on the forecast run date) for sub-seasonal. The forecast anomaly and uncertainty signals are based on the extremity level of each ensemble member, which is derived by comparing the real time forecast to the underlying model climatology. The climatology is generated using reforecasts over a 20-year period, which provides range-dependent climate percentiles that change with the lead time. Detailed information on GloFAS Sub-seasonal and Seasonal products can be found in the GloFAS Sub-Seasonal and Seasonal forecasts products wiki pages.

The GloFAS User Guide provides hands-on information on how to explore the tabs and layers of the Map Viewer.

How GloFAS Sub-seasonal and Seasonal forecasts are produced

The schematic below illustrates how the EFAS seasonal and sub-seasonal outlooks are produced. Further information on the details of the different steps generating the sub-seasonal and seasonal forecast signal and the related products is available at CEMS-Flood sub-seasonal and seasonal forecasting.
For more details on the latest GloFAS configuration, please refer to the Latest operational GloFAS release wiki page.