Form of Output

ECMWF provides data from several different IFS models, each available according to when the IFS models are run, and each with different temporal resolutions in the output data.

Output data is in the form:

  • most commonly as absolute values:  
    • instantaneous values,
    • averages over a period,
    • totals over a period,  
    • maxima or minima over a period.
  • sometimes as:

Medium range forecasts

The Control Forecast (ex-HRES) model:

The link gives a description of higher detail output and derived products of the medium range forecast output.  Some are additional products that are available by arrangement.

Note: HRES and Ensemble Control are scientifically, structurally and computationally identical.  For the benefit of users:

  • The Ensemble Control Forecast (ex-HRES) output runs on the schedule of HRES in Cy48 and earlier.   It runs before the medium range ensemble starts.  It is labelled HRES for the convenience of users but the name will be withdrawn in a future update cycle.
  • Ensemble Control Forecast (ex-HRES) also continues to be issued at the times given below, even though it is identical to the earlier issue labelled HRES.

In Cy50r scheduled for summer 2025:

  • The Ensemble Control Forecast (ex-HRES) will continue to be issued at the times given above.
  • The perturbed ensemble members will be issued at the times given below (without ensemble control forecast (ex-HRES) which will have been issued earlier).


The medium range ensemble:

The link gives a description of higher detail output and derived products of the medium range ensemble forecast output.  Some are additional products that are available by arrangement.

Note: HRES and Ensemble Control are scientifically, structurally and computationally identical.  For the benefit of users:

  • The Ensemble Control Forecast (ex-HRES) output runs on the schedule of HRES in Cy48 and earlier.   It runs before the medium range ensemble starts.  It is labelled HRES for the convenience of users but the name will be withdrawn in a future update cycle.
  • Ensemble Control Forecast (ex-HRES) also continues to be issued at the times given below, even though it is identical to the earlier issue labelled HRES.

In Cy50r scheduled for summer 2025:

  • The Ensemble control forecast (ex-HRES) will continue to be issued at the times given above.
  • The perturbed ensemble members will be issued at the times given below (without ensemble control forecast (ex-HRES) which will have been issued earlier).

The Artificial Intelligence Forecasting System (AIFS)  (Medium range)

The link gives a description of higher detail output and derived products of the Artificial Intelligence Forecasting System forecast output.

Sub-seasonal Range forecasts

The sub-seasonal range ensemble:

    • has horizontal resolution of 36 km.
    • has vertical resolution of 137 model levels.
    • has land-atmosphere and ocean-atmosphere coupling.
    • has 100 ensemble members plus an unperturbed control member.

Precipitation forecasts are provided as values accumulated from the start of the forecast integration.  The range of the daily variation of the forecast 2m temperature and wind gust is best estimated by retrieving the forecast maximum and minimum values.  The combination of accumulated and instantaneous forecast information can occasionally lead to inconsistencies as in both cases the valid time is defined as the time at the end of the period (e.g. during the passage of a cold front when significant precipitation amounts might be accumulated by the IFS models over the whole time interval though instantaneous cloud-free conditions will be shown at the end of the interval).

The link gives a description of higher detail output and derived products of the sub-seasonal range ensemble forecast output.    Some are additional products that are available by arrangement.

Seasonal (SEAS) forecasts

The seasonal range ensemble:

    • is run once monthly:
      • base time 00UTC on 1st of each month and run on the 5th of each month covering the forecast period  Month 1 to Month 7 month forecast (extended to Month 13 every quarter).
    • has horizontal resolution of 36 Km and vertical resolution of 91 model levels.
    • has land-atmosphere and ocean-atmosphere coupling.
    • has 50 ensemble members plus an unperturbed control member.


The link gives a description of higher detail output and derived products of the seasonal model output.    Some are additional products that are available by arrangement.

Wave model ECWAM forecasts

Control Forecast (ex-HRES) WAM

    • is associated with ensemble Control Forecast (ex-HRES) forecasts
    • has horizontal resolution of 9 Km.
    • has ocean-atmosphere coupling.

The link gives a description of higher detail output and derived products of the Ensemble Control Forecast (ex-HRES) WAM.    Some are additional products that are available by arrangement.

Ensemble (medium range) ensemble WAM (ENS WAM)

    • is associated with the medium range forecasts.
    • has horizontal resolution of 9 Km.
    • has ocean-atmosphere coupling.
    • has 50 ensemble members plus an unperturbed control member.

The link gives a description of higher detail output and derived products of the ensemble (medium range) WAM.    Some are additional products that are available by arrangement.

Sub-seasonal WAM

    • is run once daily:
    • is associated with the sub-seasonal range forecasts.
    • has horizontal resolution of 36 Km.
    • has ocean-atmosphere coupling.
    • has 50 ensemble members plus an unperturbed control member.

The link gives a description of higher detail output and derived products of the sub-seasonal model output.    Some are additional products that are available by arrangement.



(FUG Associated with Cy49r1)