GloFAS meteorological forecasts are produced using the latest ensemble of Numerical Weather Prediction (NWP) forecasts of the ECMWF IFS, with different model configurations used for the different GloFAS leadtimes and systems:

• Medium- and extended-range deterministic and ensemble forecasts for GloFAS 30-day. ECMWF-ENS is the ensemble of lower-resolution forecast of ECMWF and consists of 51 members at ~18 km resolution up to 15 days, increasing to ~36 km from day 16 to 30. In GloFAS 30-day, the outputs of the 00:00 UTC IFS medium-range runs are used daily for days 1 to 15, and the latest available IFS extended-range runs are used for days 16 to 30. The ECMWF-ENS-CNTL is a special member of the ENS, which uses the most accurate estimate of the current initial conditions (used also in ECMWF-HRES), while the other 50 ensemble members start from slightly perturbed conditions.
• Long-range SEAS5 ensemble forecasts for GloFAS Seasonal. SEAS5 is the ensemble seasonal forecast of ECMWF (operational since 5 November 2017), and one of the seasonal forecast models of the Copernicus Climate Change Service. It consists of 51 members at ~36 km horizontal resolution, generated each month (from the 1st of the month) with 7 months lead time (extended to 13 months once a season).