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• medium-range (day 0 to day 15) forecast products.  This output generally differs significantly from that dealing with short-range or seasonal NWP.   
• extended range (day 16 to day 42) forecasts products.  These concentrate on the probabilities of anomalies from the norm during 5-7 day forecast periods for given location and time of year.
• seasonal forecasts (month 1 to month 7 or 13).  These give an indication of likely conditions beyond six weeks ahead.  They are run monthly giving forecasts to 7 months ahead, and run quarterly with forecasts extended to 13 months ahead.  Output concentrates on the anomalies relative to the seasonal climate.  

The IFS models areconfigurations are:

• the 10-day High Resolution forecast (HRES)
• the 10-day ensemble forecast (ENS).the 15-day ensemble forecast (ENS).
• the 46-day extended range forecast including the extended range control member.
• the 7 or 13 month seasonal forecast.

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The ECMWF IFS is upgraded at roughly half yearly intervals to incorporate improved representation of physical processes and/or resolution changes.   New products increasingly aid early warning of severe or hazardous weather.  Information on the latest upgrade is given below.

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Users are advised to keep themselves updated about changes and improvements to products and model processes through the ECMWF Newsletter and web site (e.g. via the Forecast User portal)

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This User Guide has been compiled  by Bob Owens, with assistance from Tim Hewson, and with contributions from many other scientists and ex-forecasters at ECMWF. It is an updated version of the "User Guide to ECMWF Forecast Products" written originally by Anders Persson and published in 2011 (that had minor adjustments in 2013 and 2015).

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