The following is a description of the latest operational release of EFAS (version 5.5), which was launched on 10 September 2025. For an overview of other EFAS releases, please see: EFAS versioning system. 

Summary

EFAS v5.5 introduces several changes to the system, including:

  • Inclusion of ECMWF’s Artificial Intelligence/Integrated Forecasting System (AIFS) model in EFAS. 
    • Documentation about the operational release of ECMWF's AIFS model, including information on versions, is available on this dedicated AIFS webpage.
    • AIFS Single replaces the ECMWF Deterministic (ECMWF Det.) model in the meteorological forcings of EFAS: EFAS Meteorological forecasts
    • AIFS Single replaces the ECMWF Deterministic products in EFAS-IS:
  • AIFS is now included in the EFAS Hydrological Post-Processed (HPP) forecasts:
    • All post-processed stations have been calibrated using new observations up to 19 August 2025 (1948 6-hourly and 228 daily).
    • Calibration of the post-processing method was evaluated at each successfully calibrated station using the Kling-Gupta Efficiency Score and the Continuous Ranked Probability Score. Results of the evaluation are available on this page: EFAS v5.5 - Hydrological Post-Processing Evaluation
  • New naming convention of NWP forcing
    • ECMWF medium-range NWP called IFS ENS, in line with ECMWF's naming convention
    • ECMWF control member called IFS CF (equivalent to deprecated ECMWF HRES forcing)

This upgrade of EFAS changes the reporting point estimation.

Technical details

Pre-release date (available on stage platform)

2025-09-03

Release date

2025-09-10 

In test suite

n/a

EFAS internal number

20
Archiving of data

ECFS, MARS, CDS 

Reference climatology (for thresholds/ anomalies)1992-01-01 to 2022-12-31
EFAS Historical1992-01-01 to near present
Reforecasts

tbc

Horizontal projectionEPSG4326
Horizontal resolution0.01667 x 0.01667°
Temporal resolution6-hourly