Integrated Forecast System

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The Integrated Forecast System (IFS) is an operational global meteorological forecasting model. IFS is developed and maintained by the European Centre for Medium-Range Weather Forecasts (ECMWF) based in Reading, England. Because of its source, it is often known as the "ECMWF" or the "European model" in North America, to distinguish it from the American Global Forecast System (GFS). It is one of the predominant synoptic-scale medium-range models in general use worldwide; its most prominent rivals in the 6–10 day medium range include the GFS and the Canadian Global Environmental Multiscale Model (GEM and GDPS).

The IFS is a global model that runs every twelve hours. Its output runs out to fifteen days in one-day intervals (although output is only made available to most members of the public out to 7 to 10 days, depending on the variable). The operational model runs both in a deterministic forecast mode and as a 51-member ensemble. The current deterministic mode has a horizontal resolution of 16 km while the ensemble prediction systems have resolutions of 32 and 64 km, and 137 layers in the vertical resolution in the deterministic compared to 91 layers in the ensemble; both modes' vertical layers follow terrain at low levels. The IFS, like the GFS, uses spectral representation rather than a grid-based system. Because the IFS only offers output on a day-by-day interval, each individual ECMWF member country typically runs its own synoptic-scale forecast for the shorter ranges of 5 days or less, separate from the IFS, with smaller time intervals (examples include the French ARPEGE, British Unified Model and German GME/ICON).

In contrast to the GEM/GDPS (which is copyrighted but freely licensed) and the GFS (which is public domain), the ECMWF's proprietary data and forecasts are heavily restricted and require a licence for most output. A limited amount of the IFS's output is released freely to the public and licensed under a Creative Commons licence that prohibits commercial usage or derivative works.[1]


  1. ^ "ECMWF terms of use". European Centre for Medium-Range Weather Forecasts. Retrieved 24 April 2017. 

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