NOUS41 KWBC 101345



Service Change Notice 17-45

National Weather Service Headquarters Silver Spring, MD

945 PM EDT Mon Apr 10 2017.


To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network


           Other NWS Partners, Users and Employees


From:      Dave Myrick

           NWS Office of Science and Technology Integration


Subject:   Discontinue GFDL Hurricane Model:

           Effective with GFS upgrade in June 2017


In June 2017, the NWS National Centers for Environmental

Prediction (NCEP) is planning to retire the Geophysical Fluid

Dynamics Laboratory (GFDL) Hurricane Model (GHM) and replace it

with a new NOAA Environmental Modeling System (NEMS)-based

hurricane model called Hurricanes in a Multi-scale Ocean-coupled

Non-hydrostatic (HMON).


NCEP reviewed comments between Feb. 13, 2017 to Mar 17, 2017,

soliciting feedback for discontinuing the GFDL and replacing it

with the HMON system. Based on comments, NCEP will move forward

executing this plan. Please see the PNS for reference:


NCEP is reasons for retiring the legacy GFDL Hurricane Model are

as follows:


1. The Environmental Modeling Center's (EMC) efforts towards

unification of operational models within the NEMS framework.


2. NHC's evaluation and endorsement of the new HMON through

evaluation of 3-year (2014-2016) retrospective experiments run

by EMC. HMON model consistently showed improved performance for

track and intensity skill for the North Atlantic and northeast

Pacific Basins as compared to the legacy GFDL hurricane model.


3. Retirement of key personnel at GFDL leading to a loss of

support for maintaining the GFDL Hurricane model in operations.


The timing of the proposed changes will be as follows:


1. Discontinue the GHM on the date of the GFS2017 upgrade in

June 2017. This SCN will be updated with the exact date once it

is known. On that date, all GHM products will be removed from

the following:


 - NCEP servers under hur.YYYYMMDD will be discontinued:

   Where YYYYMMDD is year, month and day


 - Model Analyses and Guidance will be discontinued:


2. With the hurricane model upgrade slated for June 2017, NCEP

will start delivering the new HMON operational model on the NCEP

servers. The HMON will be equivalent to the discontinued GHM.

For sample data please reference:


Any questions, comments or requests regarding this

implementation should be directed to the contacts below. We will

review any feedback and decide whether to proceed.


Send comments on this proposal to:


     Avichal Mehra

     Lead, Physical Scientist

     NCEP/Environmental Modeling Center

     College Park, MD


     Carissa Klemmer

     NWS/NCEP Central Operations

     Dataflow Team Lead

     College Park, MD


National Service Change Notices are online at: