GloFAS forecast skill is summarised in the interactive "Forecast skill" layer under the "Evaluation" tab on the GloFAS web map viewer.

Headline forecast skill score 

The headline ensemble forecast skill score is the maximum lead time (in days), up to 15 days ahead, for which the Continuous Ranked Probability Skill Score (CRPSS) exceeds 0.5 when compared to a persistence or climatology benchmark forecast. It is provided for all GloFAS v5 calibration points. Details of the evaluation methodology can be found in GloFAS forecast skill.

For GloFAS v5, forecast skill is calculated separately for each month, rather than providing a single score for the whole year. The skill layer is updated on the first day of every month using the latest available reforecasts, allowing it to reflect both seasonal variations in forecast skill and changes in the operational forecasting system. 

The forecast skill displayed on the map depends on the selected forecast date, with the corresponding monthly skill assessment shown. This allows users to view forecast skill representative of the time of year being considered.

The headline score is displayed as colour-coded circles, with darker colours indicating skill above the threshold at longer lead times. The light-pink category (0–1 days) represents locations where the CRPSS threshold of 0.5 is exceeded for no more than one day ahead, or is not exceeded at any lead time.

Note: A CRPSS below 0.5 does not necessarily mean that the forecast has no skill at that location. A CRPSS ≤ 0 indicates that the forecast is not more skilful than the chosen benchmark (persistence or climatology).

An explanation of the persistence and climatology benchmarks is available in GloFAS forecast skill.

Pop-out graphs

Time-series skill plot showing CRPS and resulting CRPSS.