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)

  • HRES output is shown to give "deterministic" snapshots of the forecast evolution for various combinations of parameters.  It is important not to be beguiled into treating HRES charts as definitive, despite the apparent detail.  The HRES should only be considered as one member of the medium range ensemble.
    Charts available:
    • Forecast charts (surface and upper air) - showing a selection of individual and combined parameters, to 10days forecast lead-time.
      • Charts available(atmospheric):
        • MSLP and wind speed at 850hPa
        • MSLP and wind at 200hPa
        • MSLP and Rain
        • MSLP and 500-1000hPa thickness
        • Vorticity and wind at 700hPa
        • Temperature and geopotential at various pressure levels
        • Wind and geopotential at various pressure levels
        • Wind and relative humidity at various pressure levels
        • Geopotential 500hPa and temperature at 850hPa
        • 2m temperature and 30m winds
        • 2m temperature and 10m winds
        • Total cloud cover
        • Indices (CAPE/K-index/Totalx)
      • Charts available(oceanic):
        • Significant wave height and mean direction
        • Mean wave period and direction
        • Total swell: Significant wave height and mean direction
        • Total swell: Mean wave period and direction
        • Significant wind wave height and mean direction
        • Mean wind wave period and direction
    • Imagery charts:
      • IR and WV imagery charts - these are derived from the structure of the IFS model atmosphere and provide a useful comparison with satellite imagery and analysed and forecast upper air flow patterns.  They may be particularly useful for seeing whether the model is replicating small scale features in the flow. (Example IR chart, Example WV chart). 


Medium range ensemble (10 or 15 day forecast period)

  • Medium range ensemble output is shown for individual ensemble members for a few parameters.  More importantly, ensemble output showing a selection of individual and combined parameters is presented in a probabilistic or multi-valued format.  The medium range ensemble consists of 50 members plus one control member.  Charts available:



  • Model diagnostic output is shown to allow the user to assess the impact of the latest observations or the modelled state of the underlying surface of the earth.
    Charts available:
    • Analysis increment charts - to allow identification of sources of potential problems in the forecast evolution.  (Example chart).
    • Surface parameter charts - to indicate the surface conditions used by ensemble control runs that govern radiation and other exchanges with the atmosphere.  These allow the user to assess any shortcomings (e.g. insufficient snow cover, soil moisture, leaf area index etc). (Example chart).

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:

  • Weekly mean anomaly charts - to highlight areas where mean forecast values depart significantly from the ER-M-climate for each location within the chart area. (Example chart).
  • Weekly probability anomaly charts - to highlight the probability of being above the ER-M-climate mean for each location within the chart area. (Example chart).
  • Weekly probability charts - to show the probability the weekly mean anomalies will be in lower and upper quantiles of the ER-M-climate for each location within the chart area. (Example chart).
  • Weekly averages of the monthly forecast ensemble for several variables on a single chart. (Example chart).
  • Tropical cyclone probability charts (including genesis) - to indicate tropical cyclone threat and intensity worldwide and compare with tropical cyclone frequency and intensity in the ER-M-climate. (Example chart).
  • Time-longitude (Hovmoeller) diagram of the observed and forecast ensemble mean anomaly of 500hPa or 1000hPa geopotential (in dam) in the extra-tropics - to show persistence and progression of disturbances and potential interaction between upper and lower features. (Example diagram).
  • Madden-Julian Oscillation (MJO) index metrics and Wheeler-Hendon MJO diagram - to show recent and forecast evolution and uncertainty of MJO features. (Example MJO index metrics Hovmoeller diagram, example Wheeler-Hendon MJO diagram).


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.