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Home > GFS documentation

The Global Forecast System (GFS) has been in NWS operations since 1980 and is continuously improved by the Environmental Modeling Center ( whose mission is to maintain, enhance and transition-to-operations advanced numerical guidance systems for the Nation's weather/water/climate enterprise and the global community for the protection of life/property and the enhancement of the economy.

The operational GFS consists of a data assimilation system (GDAS) for the atmosphere and forecast models for the atmosphere and ocean waves. On March 17, 2020, GFS was upgraded from version 15.3 to 16.0. GFS version 16.0 is the first major upgrade to the Finite Volume Cubed Sphere (FV3) dynamical core-based GFS, which replaced the spectral dynamical core in June 2019. In this upgrade, NCEP is increasing the number of model vertical layers from 64 to 127 and extending the model top from the upper stratosphere (~55 km height) to the mesopause (~80 km height). Please see for details of this upgrade.

GFS output is posted to a quarter degree equally spaced longitude/latitude grid with a temporal resolution of 1 hour out to 120 hours, then 3 hours for days 5-16, has 57 vertical standard pressure levels, and is cycled 4x/day.

See History of recent modifications to the global forecast/analysis system at:

Model performance statistics can be found at:

Documentation homepage:


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