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Form of Output

ECMWF provides data from several different IFS models, with different frequencies 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:
  • anomalies relative to re-forecast data
  • an assessment of how extreme the anomalies might be (Extreme Forecast Index and Shift of Tails).

Medium

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Daily runs based 00UTC and 12UTC data time are available for the following forecast times:

For data:

• HRES & HRES-WAM analysis and forecasts based on 00UTC and 12UTC: hourly up to T+90, 3-hourly from T+93 to T+144, 6-hourly from T+150 to T+240.
• ENS & ENS-WAM forecasts based on 00UTC and 12UTC: 3 hourly up to T+144, 6-hourly from T+150 to T+360.

For ecCharts:

• HRES, HRES-WAM analysis and forecasts based on 00UTC and 12UTC: 3-hourly up to T+144, 6-hourly from T+150 to T+240 (day10).
• ENS, ENS-WAM forecasts based on 00UTC and 12UTC: 3 hourly up to T+144, 6-hourly from T+150 to T+360 (day15).

For Members of the Boundary Conditions (BC) optional programme (members using ECMWF IFS model forecast values as boundary conditions for their own local areas models) Medium Range forecasts based on 06UTC and 18UTC data times are available for the following forecast times:

• HRES: analysis and forecast based on 06UTC and 18UTC:  hourly up to T+90, 3-hourly from T+93 to T+144

Note: 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 theIFS models over the whole time interval though instantaneous cloud-free conditions will be shown at the end of the interval).

Definitive information on the ECMWF dissemination schedule and products can be found in the the Catalogue of ECMWF real-time products (HRES: Set i, HRES-WAM: Set ii, ENS: Set iii, ENS-WAM: Set iv).

NB: No or degraded access to these dataset at times between September and December 2021 during MARS migration to Bologna).

Extended Range forecasts

Two runs Mondays and Thursdays based on 00UTC data time, six 7-day ranges per run are available for the following forecast times :

For data:

• ENS-extended & ENS-WAM-extended: 6-hourly from T+366 to T+1104.
• ENS-extended & ENS-WAM-extended ensemble means and anomalies (output for corresponding forecast weeks) on: 
  • Mondays:       T+0 to T+168(week1),  T+168 to T+336(week2),  T+336 to T+504(week3),  T+504 to T+672(week4),  T+672 to T+840(week5),  T+840 to T+1008(week6).
  • Thursdays:  T+96 to T+264(week1),  T+264 to T+432(week2),  T+432 to T+600(week3),  T+600 to T+768(week4),  T+768 to T+936(week5),  T+936 to T+1104(week6).

For  Set :

• ENS-extended & ENS-WAM-extended ensemble means and anomalies (output is for corresponding forecast weeks) on:
  • Mondays:       T+0 to T+168(week1),  T+168 to T+336(week2),  T+336 to T+504(week3),  T+504 to T+672(week4),  T+672 to T+840(week5),  T+840 to T+1008(week6).
  • Thursdays:  T+96 to T+264(week1),  T+264 to T+432(week2),  T+432 to T+600(week3),  T+600 to T+768(week4),  T+768 to T+936(week5),  T+936 to T+1104(week6).
    

range forecasts

The "high resolution" model (HRES):

• • is run four times daily:
    • base times 00 UTC and 12 UTC, producing a 10 day forecast (T+0 to T+240).
      • Dissemination schedule - Atmospheric model ensemble 10-day forecast (HRES) and model analysis and forecast output parameters (Set I-i, I-ii, I-iii as shown for 00UTC and 12UTC base times).
      • Dissemination schedule - Ocean wave model ensemble 10-day forecast (HRES-WAM)  and model analysis and forecast output parameters (Set II as shown for 00UTC and 12UTC base times).
    • base times 06UTC and 18UTC, producing a 6 day forecast (T+0 to T+144). Results from these runs are:
      • Dissemination schedule - Atmospheric model 90 hour forecast (HRES) and model analysis and forecast output parameters(Set I-i as shown for 06UTC and 18UTC base times).
      • Dissemination schedule - Ocean wave model ensemble 90 hour forecast (HRES-WAM) and model analysis and forecast output parameters (Set II as shown for 06UTC and 18UTC base times).
  • has horizontal resolution of 9 Km and vertical resolution of 137 model levels.  These values are the same as those of the medium range ensemble.
  • has land-atmosphere and ocean-atmosphere coupling.

The medium range ensemble (ENS):

• • is run four times daily:
    • base times 00 UTC and 12 UTC, producing a 10 day forecast (T+0 to T+240) and also a 15 day forecast (T+0 to T+360).
      • Dissemination schedule - Atmospheric model ensemble 10-day forecast (HRES and CTRL) and model analysis and forecast output parameters (Set I-i, I-ii, I-iii as shown for 00UTC and 12UTC base times).
      • Dissemination schedule - Atmospheric model ensemble 15-day forecast (ENS) and model analysis and forecast output parameters (Set III as shown for 00UTC and 12UTC base times).
      • Dissemination schedule - Ocean wave model ensemble 10-day forecast (HRES-WAM)  and model analysis and forecast output parameters (Set II as shown for 00UTC and 12UTC base times).
      • Dissemination schedule - Ocean wave model ensemble 15-day forecast (ENS-WAM)  and model analysis and forecast output parameters (Set IV-i, IV-ii, IV-iii as shown for 00UTC and 12UTC base times).
    • base times 06UTC and 18UTC, producing a 6 day forecast (T+0 to T+144). Results from these runs are:
      • used in Early cut off analysis (SCDA) and Long window data analysis (LWDA).
      • disseminated T+0 to T+72.
      • Dissemination schedule - Atmospheric model 90 hour forecast (HRES) and model analysis and forecast output parameters(Set I-i as shown for 06UTC and 18UTC base times).
      • Dissemination schedule - Atmospheric model 3 day ensemble forecast (ENS) and model analysis and forecast output parameters (Set III as shown for 06UTC and 18UTC base times.  Tropical Cyclone Tracks are also available for 06UTC and 18UTC base times).
      • Dissemination schedule - Ocean wave model ensemble 90 hour forecast (HRES-WAM) and model analysis and forecast output parameters (Set II as shown for 06UTC and 18UTC base times).
  • has horizontal resolution of 9 Km and vertical resolution of 137 model levels.  These values are the same as those of the High Resolution (HRES).
  • has land-atmosphere and ocean-atmosphere coupling.
  • has 50 ensemble members plus an unperturbed control member (CTRL).
  • the unperturbed control member (CTRL) corresponds to the High Resolution (HRES).

The horizontal and vertical resolutions of the medium range ensemble (ENS) became the same as for the HRES after the upgrade to IFS (Cy48r1) introduced in June 2023.  The HRES forecast and the unperturbed ENS control forecast are meteorologically equivalent and equally skilful on average.  They have the same physical and dynamical representation of the atmosphere and use the same parameterisation of sub-gridscale effects.  However, they can diverge on a day-to-day basis due to small technical differences and the chaotic nature of the atmosphere.  The HRES will continue for the time being for ease of use by customers and users.

Extended Range forecasts

The extended range ensemble:

• • is run once daily:
    • base time 00UTC, producing a 46 day forecast (T+0 to T+960/1104).
      • Dissemination schedule - Atmospheric model ensemble extended forecast (ENS extended). See also model analysis and forecast output parameter means and anomalies (Set VI).
      • Dissemination schedule - Ocean wave model ensemble extended forecast (ENS-WAM extended). See also model analysis and forecast wave parameters and means (set VI-v-c)

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

Note:

Extended range products cover the period beyond the medium range forecasts (i.e. from day 15 to day 46).

Note: 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 theIFS the IFS models over the whole time interval though instantaneous cloud-free conditions will be shown at the end of the interval).

Definitive information on the ECMWF dissemination schedule and products can be found in the the Catalogue of ECMWF real-time products (ENS-extended: Set vi, ENS-WAM-extended: Set iv-i).

NB: No or degraded access to these dataset at times between September and December 2021 during MARS migration to Bologna).

Seasonal forecasts

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Seasonal 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

...

For data:

• Seasonal: 6-hourly ensemble means from Month 0 to Month 7, extended to Month 12 four times per year.
• Seasonal: 6hr, 12hr and 24hr output from individual forecast runs.
• Seasonal: Monthly ensemble means and anomalies means from Month 0 to Month 7, extended to Month 12 four times per year.

For ecCharts

• Seasonal: Monthly ensemble means and anomalies means from Month 0 to Month 7, extended to Month 12 four times per year.

See available Seasonal datasets for more detail of the resolution of the data and the parameters available and the dissemination schedule.

Definitive information on the ECMWF dissemination schedule and products can be found in the the Catalogue of ECMWF real-time products (SEAS: Set v).

...

• • • producing a 7 month forecast (13 months every quarter).
      
      • Dissemination schedule - Seasonal forecast (SEAS).  See also model forecast seasonal output parameter means and anomalies (set V)
      • Dissemination schedule - Seasonal forecast (SEAS).  See also model forecast seasonal output wave monthly means (set V-iii-c) and (set V-v-e))
  • 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.

Further information:

• • • Atmospheric Model high resolution 10-day forecast (Set I - HRES)

    • Ocean Wave Model high resolution 10-day Forecast (Set II - HRES-WAM)

    • Atmospheric model Ensemble 15-day forecast (Set III - ENS)

    • Ocean Wave Model Ensemble 15-day forecast (Set IV - ENS-WAM)

    • Seasonal 7-month forecast (Set V - SEAS)

    • Atmospheric Model Ensemble extended forecast (Set VI - ENS extended)