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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: is the U.S. government's official web portal to all federal, state and local government web resources and services.