The EFAS seasonal hydrological outlooks provide an overview of the likelihood of high or low flows within the next two months in a region (aggregation of river basins). They are created by comparing the EFAS seasonal forecast with EFAS low and high flow thresholds, each averaged over the defined regions.  The schematic below illustrates how the EFAS seasonal outlook is produced.

EFAS seasonal flowchart

EFAS Seasonal production chain

There are two EFAS seasonal outlook products produced for all regions at the start of each month, viewable under the ”Seasonal Outlook” layer

  • Overview map: regional discharge anomaly over the forecast horizon, highlighting regions with highest or earliest probability of a high (>90th percentile) or low (<10th percentile) discharge anomaly.

Example of EFAS Seasonal overview map
  • Time series information: weekly averages of ensemble discharge forecast as box plots, updated weekly with the latest LISFLOOD discharge simulation to help the forecaster with real-time validation.

EFAS Seasonal time series information

To know more

Arnal, L., Cloke, H. L., Stephens, E., Wetterhall, F., Prudhomme, C., Neumann, J., Krzeminski, B., and Pappenberger, F., 2018: Skilful seasonal forecasts of streamflow over Europe? Hydrol. Earth Syst. Sci., 22, 2057-2072,