The Global Forecast System The Global Forecast System

The Global Forecast System (GFS) is a global numerical weather prediction system containing a global computer model and variational analysis run by the U.S. National Weather Service (NWS).

The mathematical model is run four times a day, and produces forecasts for up to 16 days in advance, with decreased spatial resolution after 10 days. The model is a spectral model with a resolution of T1534 from 0 to 240 hours (0-10 days) and T574 from 240 to 384 hours (10-16 days). In the vertical, the model is divided into 64 layers and temporally, it produces forecast output every hour for the first 12 hours, every 3 hours out to 10 days, and every 12 hours after that.


Contacts:

Modeling and Data Assimilation Branch - Vijay Tallapragada

Website and Experiment Help - Kate Howard

Global Forecast System Documents Global Forecast System Documents

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Recent Implementations & RFCs Recent Implementations & RFCs

RFC #3622 – GFS v14.0.2 - Fixed a GFS AWIPS 20 km grid potential vorticity (PV) surface level issue

This update fixed a GFS AWIPS 20 km grid potential vorticity (PV) surface level issue for CONUS, Alaska, Puerto Rico, and Pacific Regions. Implemented on August 10 at 1800Z.

RFC #3614 – GFS v14.0.1 - Fixed the GFS AWIPS Alaska 20 km grid u- and v-wind level issue

Fixed the GFS AWIPS Alaska 20 km grid u- and v-wind level issue that was introduced in the FY17 GFS upgrade using WGRIB2 interpolation. For the AWIPS Alaska 20 km grid, modified the option in WGRIB2 for interpolation to correct the wind rotation from 'wind related to earth'-oriented to ‘wind grid’-oriented and corrected the resolution and component flags from 48 to 56 in grid definition template 3.20. This change applied to the Polar Stereographic projection for the AWIPS Alaska 20km grid. Implemented on August 4 at 2000Z.

RFC #3526 – GFS v14.0.0 - The Global Forecast System (GFS) is being upgraded to v14.0.0

Implemented on July 19 effective with the 1200Z cycle. Major changes include:

  • Implementing the Global Spectral Model (GSM) in the NEMS framework
  • Replacing spectral output files with nemsio binary files
  • Upgrade deep and shallow convection schemes
  • Changes to the GDAS and Tropical Storm Relocation
  • Changes to post-processing and output products.

Full details of the upgrade can be found at: http://www.nws.noaa.gov/os/notification/scn17-67gfsupgrade.htm

Future Implementation Plans Future Implementation Plans

Planned for FY18/19: FV3GFS

Click on "Implementations" above for more information.