NOUS41 KWBC 191450



Service Change Notice 17-104

National Weather Service Headquarters Silver Spring MD

1050 AM EDT Tue Sep 1313 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:   Global Ensemble Forecast System (GEFS) SST

           Replacement Effective September 26, 2017


On or about September 26, 2017, beginning with the 1200

Coordinated Universal Time (UTC) run, the National Centers for

Environmental Protection (NCEP) will update its Global Ensemble

Forecast System (GEFS).


The upgrade in the GEFS production suite includes:


1. Replacing the initial Sea Surface Temperature (SST) with the

foundation temperature from the global Near-Surface Sea

Temperature (NSST) analysis. This update removes cycle-to-cycle

changes due to the diurnal cycle of SST, which were introduced

into the Global Forecast System/Gridded Statistical

Interpolation (GFS/GSI) by a recent implementation but is not

modeled in the GEFS.


The GEFS products disseminated over NOAAPORT will via the NWS

and NCEP Web Services will not change in format or content.

These products are available at the following locations:


NCEP Web Servers:






NWS Web Server:




Where YYYYMMDD strings represent the Year, Month, Day value and

CC is the model cycle.


NCEP would encourage all users to ensure their decoders are

flexible and are able to adequately handle changes in content

order, parameter fields changing order, changes in the scaling

factor component within the Product Definition Section (PDS) of

the GRIB files and also any volume changes which may be

forthcoming. These elements may change with future NCEP model

implementations. NCEP will make every attempt to alert users to

these changes prior to any implementation.


Any questions, comments or requests regarding this change should

be directed to the contacts below. We will review any feedback

and decide whether to proceed.


For questions regarding these changes, please contact:


    Dingchen Hou

    NCEP/EMC Modeling and Data Assimilation Branch

    College Park, Maryland

    Phone: 301-683-3707


For questions regarding the dataflow aspects of this dataset,

please contact:


    Carissa Klemmer

    NCEP/NCO Dataflow Team Lead

    College Park, Maryland



National Service Change Notices are online at: