New GFS grid 0.25° model

By a notification corrected the 23 December 2014 (¹), the NWS (National Weather Service) NOAA has announced a major update of its weather predictions GFS model to be effective in mid-January 2015. Actually, This model is partially available on an experimental basis since early December.


The Global Forecast System (GFS) is a model of weather forecasts produced by the National Centers for Environmental Prediction (NCEP) dependent of the NWS. Dozens of variables (²) atmospheric and terrain are available through this data set, Since temperatures, winds and precipitation to moisture from the soil and the concentration of atmospheric ozone. The world is covered by the current GFS model with a horizontal resolution 27 km between grid points to 10 days. The horizontal resolution is 70 km for forecasts between one week and two weeks. The GFS model is a coupled model, composed of four distinct models (an atmospheric model, an ocean model, an Earth model, and a sea ice model), who compete together to give an accurate picture of weather conditions. Changes are regularly made to the GFS model to improve the performance and accuracy of forecasts. Gridded data are available for download via the NOMADS servers (National Operational Model Archive and Distribution System) and widely used by application developers in the world.

New model GFS / Global Spectral Model V.12.0.0

The National Centers for Environmental Prediction (NCEP) has updated the GFS global prediction and analysis system, This includes, amongst many improvements :

  • Modification of the components of the model
  • Increased horizontal resolution
  • Adding a horizontal grid data output 0,25 degrees
  • Adding new data fields
  • Modification of the naming of the products
  • Modification of the updating of the products
  • Modification of the impact on downstream models

Many other improvements concern the acquisition and assimilation of data, and in particular satellite observation data, taking into account new variables in surface (land and ocean), modeling, the rhythms of the calculations, etc.

The resolution of the model is doubled :

  • Increase of the horizontal resolution for the first segment of the reduced forecast of ≈27 ≈13 km km, with extended from forecast 192 hours 240 hours.
  • Increase of the horizontal resolution for the second segment reduced by ≈84 km at ≈35 km, with a forecast of 240 hours 384 hours.


Analysis comparative retrospective of the new model GFS compared to the current model, and also to the European of the ECMWF model, focused on some sensitive weather events, as the cyclone "Sandy"., has been presented by the NCEP (³). She was able to highlight the following results :

  • Improvement of qualification of precipitation.
  • Improvement of track of hurricanes in the Atlantic and Western Pacific, but deteriorated in the Eastern Pacific.
  • Errors of hurricane intensity reduced in all basins.
  • Errors of trajectory of storms reduced in mid-latitudes.
  • Reduction of the tendency of the global mean temperature in the upper troposphere. Improved wind data, tropospheric winds strengthened but stratospheric winds slightly weakened.
  • Improvement in the rate of the surface anomaly correlation 500 hPa in the northern hemisphere and South.

It is interesting to note that NCEP, precision models showed gaps facing those of the ECMWF in the path of the Sandy storm in October 2012, with the dramatic consequences that we know, has developed double mouthfuls to catch up.

New product output GFS to GRIB-2 native format :

  • 0.25 ° horizontal grid (15 NM), Date 0 to 240 hours (0 to 10 (j).) by 3 hours, and 240 to 384 hours (10 to 16 (j).) by 12 hours.
  • Models with average resolution of 0.5 ° and 1 ° now use the same characteristics (deadlines and not).
  • The model low resolution of 2.5 ° is planned to be abandoned in the short term because very little used.
  • GRIB-2 native output format, and rather than GRIB-1 converted.

The operational availability of these new products is estimated around mid-January 2015 (). It is in testing since early December 2014.

What improvements to boating ?

The availability of the file GRIB of the new GFS model with a mesh size of 0.25 ° (15NM), and therefore a density of data four times greater than the model 0.5 °, will undoubtedly bring a real improvement in global forecasts, especially in coastal areas and the pool closed (Mediterranean Sea, Baltic Sea) or the impact of land-based data is important. The integration of new relevant data such as the winds satellite data, a fast data acquisition, a better consideration of certain variables as those of the ice or the surface of the soil analysis, contribute to the overall improvement of the model. In addition, the impact will be also sensitive on models to fine mesh WRF, themselves impacted by the GFS model.

Comparison GFS 0.5 ° and 0.25 ° on Atlantic coast

This promises a significant progress of the global predictions for mariners, Thanks to a free broadcast by the US administration. In the meantime always making available public forecasts of the European centre of meteorology, but it is another story… ()

(¹) Technical Implementation Notice 14-46 corrected
(²) Up to 366 data striped on 64 altitude levels.
(³) GFS-ppt-GFS implementation_Q1FY15_review_v4.pptx
() Advocacy for free European data


4 Replies to “New GFS model with 0.25 ° mesh”

  1. Hello,
    Bravo for your Blog... I'm not in the Apple Galaxy, but I am interested. In your introduction, you write : "The whole world is covered by the current GFS model with a horizontal resolution of. 27 km.
    Unless I am mistaken, the resolution is 0.5 ° or 30 miles roughly 57 km... Is it of a typo ??? or Gilliam me - I ???

    1. The horizontal resolution 27 km, just be reduced to 13 km, concerning the internal development of forecast model called GDAS. The GFS model at 0.5 ° or 0.25 °, derived in part from the GDAS, concerning the output in GRIB format for public use.

  2. The Americans have imposed at the expense of Glonass and Galileo GPS, by being the first to make its free use for the general public. They do this now with weather data. Maybe also will they continue with charts ? This already starts with the NOAA charts.
    It's a shame that the France and Europe are behind on this subject.

  3. I was also able to test this model with W4d android. It's great on land, at sea a bit less files are much larger than the classical GFS. At the start of the Marquesas Islands, a little difficult to go to Tahiti weather situation. 3 depressions, the second classified level cyclone 1. Subsequently it will weaken, the third will even fill, but before leaving a forecast of such finesse for 10 days, covering the world, nothing better now and if in doubt, at sea I go back to the good old GFS, and then especially strongly that Olivier implements it on the W4D IOS version.

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