This is a description of EFAS v4.0. For an overview of other EFAS releases, please see: EFAS versioning system


EFAS 4.0 follows a complete upgrade of EFAS hydrological modelling system, with effect on all EFAS flood forecast products except ERICHA nowcasting; it also includes a number of new products and some changes in the way the flood alerts are calculated, as well as some minor changes in the web interface and general bug fixes.

Here is a a summary of the main changes:

  • Hydrological modelling upgraded to 6-hourly time step for all EFAS products
  • Upgrade of some static fields used in the hydrological modelling
  • Recalibration of the hydrological model using 1137 river stations across the EFAS domain
  • Upgrade of the statistical post-processing layer with new calibration and availability for over 1000 stations
  • Medium-range return periods thresholds updated across the EFAS domain
  • Forecasts weights for total probability updated (same weights for all forecasts)
  • Three new static layers describing some hydrological modelling features (drainage network, location of lakes and reservoirs, location of fixed reporting points)
  • Upgraded reporting points pop-up window graphics and tables:
    • Plots accommodated to 6-hourly time step and show the initial conditions
    • Modelled discharge hydrograph plots now available (with return period axis)
    • Persistence table showing most recent forecasts on top
  • New medium-range forecast performance layer
  • Improved hydrological modelling performance layer
  • Re-organisation of the layers menu for a more intuitive navigation
  • One-click icon to access the EFAS wiki
  • EFAS medium-range reforecasts  available through MARS and CDS
  • EFAS real-time seasonal forecasts and seasonal reforecasts available through MARS and CDS (from 10 November 2020)
  • Added support for flash floods feedback, through simplified "yes/no" feedback form.

EFAS 4.0 Evaluation Results

Technical details

Release date2020-10-14 12UTC
In test suite

2020-07-08 12 UTC

EFAS internal release

Archiving of data


Reference climatology (for thresholds/ anomalies)1991-01-01 to 2017-12-31
EFAS Historical1991-01-01 to near present
Horizontal projectionETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA)
Horizontal resolution5 x 5 km
Temporal resolution6-hourly for medium range-monthly products, 24-hourly for seasonal