Historical model performance and forecast evaluation is important to understand the strengths and weaknesses of the system and to build confidence in its results. The model performance and the skill of the operational medium-range forecasts is summarised using a set of metrics which highlight different aspects of model simulations and forecasts.


EFAS performance is regularly evaluated for specific events and summarized in the Validation and skill scores page.

EFAS-IS presents three different products in the Evaluation tab:

  1. Medium-range forecast skill
  2. Model performance – Catchments
  3. Model performance – Points

 

Medium-range forecast skill

The skill of the ECMWF-ENS re-forecasts produced with the Lisflood hydrological model for the period 1999-2018 using the continuous ranked probability skill score (CRPSS). The ECMWF-ENS re-forecasts are for reference year 2019 and are initialized twice per week with 11 ensemble members in each initialization. The model runs at a 6-hourly resolution and forecasts extend up to 46 days ahead.


The forecast persistence is used as a benchmark which is the 6-hour river discharge from the previous time step. The forecasts are evaluated against proxy observations at more than 2650 fixed reporting points. CRPSS values greater than 0 indicate positive skill, with a value of 1 indicating a perfect forecast. CRPSS values less than 0 indicate that the benchmark performs better than the EFAS medium-range forecast system.


The forecast skill outlook does not present the CRPSS directly but instead presents the maximum lead time (in days) when EFAS medium-range river discharge forecast skill (CRPSS) is greater than 0.5.