Dashboard

The Global Forecast System (GFS)

1) Overview

From 1980-2019, NCEP ran a global spectral model in the various production slots allocated for it. Its evolution in the NCEP Production Suite can be tracked in the table below, and documentation on the GFS spectral model can be found here.

In 2017, the Finite Volume Cubed Sphere (FV3) dynamical core, developed at NOAA’s Geophysical Fluid Dynamics Laboratory, was selected for the new Unified Forecast System (UFS) atmospheric model for both global and regional scales. At NCEP, the FV3 dynamical core implementation included incorporating FV3 into NEMS, and developing advanced physics and data assimilation techniques to match or exceed the skill of spectral model-based Global Forecast System (GFS). In addition, NOAA/NWS is working with federal partners, universities, and the community to create a fully accessible FV3-based community model, see the UFS Community page and the UFS Weather Model page on GitHub.

The first implementation of the UFS Atmospheric model in NCEP occurred on June 12th 2019 with the deployment of GFS Version 15 in the NCEP Production Suite (NPS). The major component of this implementation was to replace the Global Spectral Model in the GFS with the FV3 dynamical core. The operational GFS version 15 runs the same physics as the previous GFS, except that the Zhao-Carr microphysics was replaced with the more advanced GFDL microphysics scheme. More details on the 2019 implementation of the GFS version 15 can be found in the NWS Service Change Notice for this change, on EMC's GFS page on the NWS Vlab site, or at the "Recent GFS Implementation details" link above. Comprehensive information on the official evaluation of GFS v15 is available at the EMC GFS V15 Model Evaluation Group’s (MEG) web site.

On March 22th, 2021, NCEP implemented GFS version 16. In addition to the numerous model and data assimilation changes that are described in the NWS Service Change Notice, with this upgrade, NCEP is merging the operational standalone global deterministic WAVEWATCH III based wave model Multi_1 into the GFS system. An updated version of the WAVEWATCH III model has been coupled to the GFS using a one-way coupling scheme in which the atmospheric model provides forcing to the wave model using the NOAA Environmental Modeling System (NEMS). Additional information can be found on the EMC Model Evaluation Group’s GFS v16 website, which includes numerous links to presentations showing details on GFS v16 model/assimilation changes and performance evaluations.

The following table shows the evolution of NCEP global model since 1980, also see https://www.emc.ncep.noaa.gov/gmb/STATS/html/model_changes.html

Year

Model

Horizontal

Resolution/Vertical Layers

Forecast length

Note

Documents

1980

Spectral; Eulerian

R30L12

48h

Rhomboidal Truncation

1983

Spectral; Eulerian

R40L12

240h @ 00Z

MRF

1985

Spectral; Eulerian

R40L18

240h @ 00Z

MRF

1987

Spectral; Eulerian

T80L18

240h @ 00Z

MRF, triangular truncation

1991

Spectral; Eulerian

T126L18

240h @ 00Z

MRF

1993

Spectral; Eulerian

T126L28

240h @ 00z

MRF, SAS convection

2000

Spectral; Eulerian

T170L42 to 144h, T62L28

384h @ 00Z, 84h @ 06/12/18z

MRF/AVN, Prognostic ozone; NASA SW

2002

Spectral; Eulerian

T170L42 to 144h, T62L28 to 384h

384h 4x/day

RRTM LW

2002

Spectral; Eulerian

T254/64 to 84h, T170/42 to 180h, T126/28 to 384h

384h 4x/day

Now called GFS

2005

Spectral; Eulerian

T382L64 to 180h, T190L64 to 384h

384h 4x/day

2L OSU to 4L NOAH LSM

2007

Spectral; Eulerian

T382L64 to 180h, T190L64 to 384h

384h 4x/day

Hybrid-sigma vertical coordinate, GSI analysis

2010

Spectral; Eulerian

T574L64 to 192h

T190L64 to 384h

384h 4x/day

RRTM SW; TVD tracer transport

NWS TIN

2012

Spectral; Eulerian

T574L64 to 192h,

T190L64 to 384h

384h 4x/day

Hybrid variational ensemble (T254) DA 

NWS TIN

2015

Spectral; Semi-Lagrangian

T1534L64 to 240h

T574L64 to 384h

384h 4x/day

NWS TIN

2016

Spectral; Semi-Lagrangian

T1534L64 to 240h

T574L64 to 384h

384h 4x/day

4D Hybrid Ensemble-Variational Data Assimilation; 

NWS TIN

2017

Spectral; Semi-Lagrangian

T1534L64 to 240h

T574L64 to 384h

384h 4x/day

NEMS ; NSST

NWS SCN

2019

FV3

13 km / 64 levels

384h 4x/day

Increase resolution of ensemble DA from 35km to 25km; GFDL Microphysics 

NWS SCN

2021

FV3

13 km / 127 levels

384h 4x/day

One-way coupling to NCEP wave model

NWS SCN

2) GFS v15 Documentation

GFSv15 Service Change Notice

EMC Model Evaluation Group’s (MEG) GFSv15 web page

GFSv15 MEG Evaluation Summary

NCEP/EMC Change Control Board Presentation

GFSv15 NOAA/NWS Evaluation Summary

NCEP Office of the Director Science and Decisional Brief on GFSv15

3) GFS v16 Documentation

GFSv16 Service Change Notice (for science / output changes)

GFSv16 Service Change Notice (timing changes for downstream NCEP Production Suite systems)

EMC MEG GFSv16 page

NCEP/EMC Change Configuration Board Presentation

GFS Wave vs. Multi-1 Evaluation Summary

GFSv16 Field Evaluations (Waves/Days 1-10 Weather)

GFSv16 NWS SOO Team Evaluation Overview

GFSv16 EMC MEG Evaluation and Overview

NCEP Office of the Director Science and Decisional Briefing: Summary

NCEP Office of the Director Science and Decisional Briefing: Field Evaluations