The following is a description of the upcoming latest operational release of EFAS (v5.4), which was launched for testing on the EFAS Stage Platform on 5 March 2025. The operational release is expected on 12 March 2025 with the 12:00UTC forecasts. For an overview of other EFAS releases, please see: EFAS versioning system. 

Summary

EFAS v5.4 introduces several minor changes to the system, including:

• Upgraded seasonal and sub-seasonal products, including:
  • Similar methodologies for both seasonal (monthly anomalies) and sub-seasonal (weekly anomalies) products, with now both basin averages and river network information available. 
  • Expected forecast anomaly and associated uncertainty signal generation based on the anomaly of individual ensemble members against reforecast-based climatological distributions
  • Selectable forecast horizon for the river network and basin summary outlook maps
  • Pop-up windows showing the evolution of antecedent conditions and forecast anomalies against background climatology with details on forecast probabilities and expected anomalies for selected reporting points
  • For details on the products and methodology see: Hydrological Products Overview, EFAS Seasonal Outlook, EFAS Sub-seasonal Outlook, CEMS-flood sub-seasonal and seasonal forecast product generation methodology & EFAS sub-seasonal and seasonal forecasting.
• The EFAS medium-range forecast skill layer has been updated in two key ways:
  • Expanded Reforecast Coverage: In EFAS v5.0, the forecast skill layer was initially calculated using only the reforecasts for April, May, and June, which were the months available at the time of release. The forecast skill layer in EFAS v5.4 has now been recalculated using a complete set of reforecasts, covering the entire year. For details see: EFAS forecast skill product and EFAS forecast skill score
  • Expanded Reporting Point Network: The forecast skill calculation now includes all reporting points, incorporating the 355 new stations introduced in EFAS v5.3.
• New radar-based urban flash flood experimental products, updated every hour, available on EFAS-IS ()
  • Radar-based urban flash flood hazard product highlights 1-km urban grid cells where risk of flash flooding due to intense rainfall over the next 6-hours
  • Radar-based precipitation hazard product showing ellipses where intense storm cells could lead to urban flash flood hazards over the next 3 hours
  • The products are experimental and not monitored operationally
• New Static Layer - Flood inundation scenarios
  • Displays the modelled flood inundation extents associated with return period scenarios of 10, 50, 100 and 500 years (10%, 2%, 1% and 0.2% annual exceedance probability respectively)
• Update on Hydrological Post-processed (PP) products
  • A banner in the ReportingPoints pop-up window appears when the ensemble forecast mean exceeds either the 5th percentile or the maximum simulated value in the calibration range. This is to highlight the fact that the EFAS post-processed hydrographs are expected to be less accurate at these extreme magnitudes.
• Revamp of the EFAS Feedback page
  • Provides better integration with the existing Notification details page 
  • Adds two new Feedback related pages:
    • List of feedbacks submitted by your partner - https://european-flood.emergency.copernicus.eu/react/feedbacks/partner/
    • List of notifications that your partner has not submitted any feedback to - https://european-flood.emergency.copernicus.eu/react/feedbacks/partner/due/

This upgrade of EFAS has no impact on the EFAS modelling results.

Technical details