THE NEXT GDAS/GFS
The GFS 4D hybrid EnVar data assimilation has been approved for implementation in May 2016. Upgrades to the operational GFS include:
4D hybrid ensemble-variational data assimilation: The ensemble provides an updated estimate of situation dependent background error every hour as it evolves through the assimilation window. This flow dependent statistical estimate is combined with a fixed estimate.
Improved use of satellite radiances
Improved use of satellite winds and aircraft observations
Corrections to land surface to reduce summertime warm, dry bias over Great Plains
Two of the retrospectives were run by NCO. Retrospectives are now finished. There was an EMC CCB on March 8 and an NCEP directors briefing on March 17. A 30 day parallel for IT checkout purposes only is scheduled to begin in April. The improved system is scheduled to be implemented May 17.
A consistent parallel feed of gridded data is being planned for paraNOMADS.
Files from the real time parallel and 1 degree files from the retrospectives are on WCOSS.
Verification of the real time parallel can be found at:
Climate Prediction Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalCPC.docx
Additional power points http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/030316GFSXCPC.pptx
Additional power point http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/030316GFSXNHC.pptx
Ocean Prediction Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/GFSXopc.pptx
Storm Prediction Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalSPC.docx
Additional power point http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/SPCGFS2016.pptx
Space Weather Prediction Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalSWPC.docx
Weather Prediction Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalWPC.doc
NWS Regional Headquarters
Meteorological Development Laboratory http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalMDL.docx
National Water Center http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/EvalNWC.docx
Dowstream testing progress report http://www.emc.ncep.noaa.gov/gmb/noor/4dGFS/docs/030316GFSXHWRF.pptx
Near the top on the left is a link labelled Precip QPF. This will take you a page where you can find verification plots over CONUS for precipitation forecasts by the operational and experimental (GFSX ) GFS for a wide range of dates. If you go to the bottom on the left, there are 2D maps showing the current forecasts from the operational and parallel GFS. By 00z there is a link to arch. This will take you to an archive over the past few years for synoptic maps for different regions for the operational and parallel GFS. Note that the parallel GFS is whatever was running that day. Only since Nov. 1 2015 have we been running the current GFSX with the land surface correction.
Another site for precipitation verification is
These sites are subject to the availability of the computers to EMC and may not be up to date every day.
GEMPAK plots are being produced from the real time parallel and can be seen at:
and can be compared to the operational gfs at:
Western Region has a side by side display of the operational and parallel GFS for North America and the North Pacific:
Ocean Prediction Center displays both the GFSX and operational GFS 9950 sigma winds and has difference fields for wind and EMSL.
http://www2.opc.ncep.noaa.gov/eval/evaluation.phpClick on GFS Evaluation.
A real time comparison of soundings from the GFS and GFSX can be found at:
EMC Objective Verification
An extended version of the real time parallel can be found at:
Please note that an additional analysis change from the operational not in the current parallel was in pr4devb until the forecast initialized Oct. 31 18 GMT. It was suspected that this change may have hurt the forecasts and it was removed and is not in any of the retrospectives below.
Verification covering all retrospectives from 2013 to 2016 can be found at (The page is a work in progress):
Verification for each of the seven retrospectives covering Sandy, 3 summers and 2 winters can be found at:
http://www.emc.ncep.noaa.gov/gmb/wd20rt/vsdb/pr4devbs12/ covering Sandy.
(This covers from the 13 km implementation to the end of the winter.)
(This covers from Nov. 2014 up to the 13 km implementation in January 2015.)
A comparison of hurricane track and intensity skill
The global branch has offered to plot maps for specific cases from the retrospectives and has solicited specific cases and specific fields to look at. Western, Central, Southern and Alaska Regions have sent in cases to look at. NHC and WPC are working with the global branch to enable their evaluation of the new GFS.
MEG review of case studies proposed by WPC, Western Region and Central Region
MEG review of additional case studies
Presentation to WPC on case studies
Global Branch Meeting Summary of Western Region case studies and one Central region case study
Global Branch Meeting Summary of another Central Region case study, Alaska case study and Southern Region case study
Four case studies requested by Western region are in:
A case study requested by Central Region for Jan. 29 2015 is in:
A case study for Central Region for March 23, 2015
A case study for Central Region for July 6, 2015
Hurricane Joaquin and South Carolina flooding
Blizzard of January 22-23, 2016
A case study for Dec. 5-6, 2013 requested by Southern Region
Precipitation cases for WPC
A comparison of operational and experimental GFS forecasts for Atsani is shown in
Forecast tracks for Sandy plotted by initial time can be found at
Documents and evaluations
The official letter asking for evaluation of the GFSX
Data assimilation changes in the new GFS
Hybrid 4D EnVar
Preliminary evaluation presentation to EMC
Warm dry bias over Great Plains in summer
MEG presentations reviewing the new GFS
MODE evaluations of new GFS
Extratropical storm tracks
This is a new implementation procedure and very much work in progress. The global branch wants a thorough evaluation of the GFSX and values your insight. Please be patient and persistent with us.