Open Access Charts

A range of ECMWF output is available in chart form and can be found through the Open Access Charts Catalogue of the ECMWF website.   Most charts show a pre-formed combination of forecast products (e.g. MSLP and precipitation, relative humidity and wind at 850hPa, etc, but some have the flexibility to change parameter values (e.g. change to relative humidity and winds at 700hPa).  

Charts are generally at 24hr intervals, but some are at 12hr or 6hr intervals, and the user can select the interval required on a few.  Most chart options allow the user to select from a list of pre-defined geographical areas.

Forecast charts on this page fall into three forecast ranges:

HRES output (10 days forecast period)


Medium range ensemble (10 or 15 day forecast period)



Extended range ensemble (16-46 day forecast period)

Extended range ensemble products are derived from an extension of the normal 15 day ensemble twice per week on Mondays and Thursdays and act as a bridge in time between ensemble forecasts and seasonal forecasts.  The charts available cover week-long periods (i.e. 7-day periods after the data time of the forecast run, going up to day46).   The extended range ensemble consists of 100 members plus one control member.
Charts available:


Long Range or Seasonal ensemble (7 to 13 months period)

Long-range or Seasonal forecast charts are derived from an ensemble (separate from the extended range ensemble) run on the 1st of each month out to 7 months, extended to 13 months each quarter (i.e. every 3 months).   The charts available mostly cover 3-month periods, with the first valid period typically beginning 1 month after data time.
Charts available:


Verification Metrics for Extended Range and Long Range forecasts

Provided alongside the forecasts are measures of the skill (Relative Operating Characteristics (ROC) and reliability that were "achieved" within the respective re-forecast periods.  Forecasters should always consider forecasts at these longer lead times in the context of these verification scores.  Using verification metrics to aid assessment of the predictability.  (Example ROC diagram, example reliability diagram).


Updated/Amended 25/10/20 - amended chart links to open access.