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Update: June 12, 2019

As of the 12Z cycle of GFS on June 12th, 2019, this next generation GFS has moved into production. GFS is now at version 15.1, which contains the FV3 core and all the other related updates.

Any requests for this next generation GFS data will continue to work, however it is now the same data as the normal GFS model in LuckGrib.

When NOAA makes the next versions of GFS available to the public for evaluation, LuckGrib will try to make it available, in the same way that FV3-GFS was made available over a year before it became the official GFS version.

The rest of this page is left for historical purposes.

Note: when NOAA was running this parallel version of GFS, its data appeared a few hours later than the production version of GFS. In order to encourage everybody to migrate off of this research model and onto the production GFS, I am leaving that delay in place. This research model appears two or three hours later than production GFS - you might want to use GFS instead!

Second note: another reason to migrate away from this research version of GFS is that it may be going away soon. It will be kept around for a short while to allow people to move away from it, but note that it may disappear at some point (and then reappear when there is new research data to explore.)

Description

NOAA’s National Weather Service Environmental Modeling Center is responsible for the GFS model. As of the time this article was written (July 2018) the most recent update to GFS was July 19, 2017, when version v14 of GFS was put into production. There has been a continual series of improvements to the GFS, roughly once per year.

There is a planned update to GFS, from v14 to v15, in Q2FY19 (January to March, 2019.) This next version of GFS represents a major change from the existing version.

The following is from the NOAA public information statement:

NOAA/NWS selected the Geophysical Fluid Dynamics Laboratory (GFDL) finite-volume cubed-sphere (FV3) dynamical core as the NWS Next Generation Global Prediction System (NGGPS). The Environmental Modeling Center (EMC) is seeking comments on the proposed changes to the Global Forecast System (GFS) running with FV3 through July 15, 2018.

The current operational GFS, which has a spectral dynamical core, will be replaced by the proposed GFS with FV3 dynamical core and improved physics parameterizations in Quarter 2 of Fiscal Year 2019 (Q2FY19). We are seeking feedback on the performance of the GFS with FV3 and the proposed product changes.

The proposed GFS version maintains a horizontal resolution of 13km and has 64 levels in the vertical extending up to 0.2 hPa. It uses the same physics package as the current operational GFS except for:

• Replacing Zhao-Carr microphysics with the more advanced GFDL microphysics
• Updating parameterization of ozone photochemistry with additional production and loss terms
• Introducing parameterization of middle atmospheric water vapor photochemistry
• Revising bare soil evaporation scheme

The data assimilation system will be updated to include:

• Infrared Atmospheric Sounding Interferometer (IASI) moisture channels
• Advanced Technology Microwave Sounder (ATMS) all-sky radiances
• Fix for an issue with the Near Sea Surface Temperature (NSST) in the Florida Strait
• Upgrade to the use of Cross-track Infrared Sounder (CrIS) radiances
• NOAA-20 CrIS and ATMS data
• Megha-Tropiques SAPHIR data
• Advanced Scatterometer (ASCAT) data from MetOp-B

– https://www.weather.gov/media/notification/pdfs/pns18-15gfs-upgrade.pdf

There is also a blog post available which describes the upgrade of GFS in more detail.

NOAA is running the next generation GFS in parallel with the current version and is making the data from the upgraded model available. As there appears to be general interest in the weather community surrounding this planned upgrade, the data from the updated model is being made available through LuckGrib.

You should note that this data is being evaluated by the weather community and additional changes to the model as problems are identified and fixed are possible. Also note that if you read through some of the supporting documents provided by the Model Evaluation Group, there have been a variety of problems identified in the upgrade, as you would expect with such a large change, which have been identified and fixed. There is no guarantee that there are not problems remaining in the data.

If you need weather data for mission critical applications, I suggest you avoid this model. If you are interested in evaluating this new model and comparing it to other weather models that are available, please feel free to access it.

Note on sea level pressure

See this blog post for a note on the mean sea level pressure (PRMSL) paramter in the GFS data delivered by LuckGrib. A quick summary is that as of August 28, 2018, an improved mean sea level pressure parameter is being used. This new parameter has a higher resolution and is able to resolve smaller features, such as tropical cyclones.

Supporting documents

There is some additional information which may be of interest.

• The Model Evaluation Group’s evaluation of FV3 GFS is here

• A site which allows you to compare GFS and FV3 GFS to each other is here

• GFS on wikipedia. This link has a brief discussion of FV3

• An in-depth description of FV3 itself

• The public information statement