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. See the JNWPU/NMC/NCEP Global/Hemispheric Model History Page for a list of all Global/Hemispheric Models from 1958-Present.

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