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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 Global Climate and Weather Modeling Branch which conducts a program of research and development in support of the Environmental Modeling Center (EMC) ( of the National Centers for Environmental Prediction (NCEP) (

The operational GFS consists of the final Global Data Assimilation System (GDAS), the GFS forecasts, and the Ensemble forecasts (GEFS). The GFS is a consolidation of the forecasts formerly known as the Aviation (AVN) and the Medium Range Forecast (MRF). GFS version 15.1 uses the FV3 dynamical core which was developed by the Geophysical Fluid Dynamics Laboratory (GFDL) under NOAA's Office of Atmospheric Research (OAR). The model is based on the usual expressions of conservation of mass, momentum, energy, and moisture and has an approximately 13 km physics (Gaussian) grid and 64 levels in a hybrid sigma-pressure vertical coordinate.

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 46 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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