[nws-changes] 20120312: GEFS Fwd: ADMIN NOTICE NOUS41 KWBC

• To: nws-changes@xxxxxxxxxxxxxxxx
• Subject: [nws-changes] 20120312: GEFS Fwd: ADMIN NOTICE NOUS41 KWBC
• From: Linda Miller <lmiller@xxxxxxxxxxxxxxxx>
• Date: Mon, 12 Mar 2012 06:46:06 -0600

-------- Original Message --------

918
NOUS41 KWBC 121110
PNSWSH

Technical Implementation Notice 12-11
National Weather Service Headquarters Washington DC
710 AM EST Mon Mar 12 2012

To:        Subscribers:
           -Family of Services
           -NOAA Weather Wire Service
           -Emergency Managers Weather Information Network
           -NOAAPORT
           Other NWS Partners, Users and Employees

From:      Timothy McClung
           Chief, Science Plans Brach
           Office of Science and Technology

Subject:   Change to Land/Water Bitmask in Select GEFS
           Products: Effective April 17, 2012

On or about Tuesday, April 17, 2012, starting with the 1200
Coordinated Universal Time (UTC) model distribution, the
National Centers for Environmental Prediction (NCEP) will make a
minor modification to a few output products from the Global
Ensemble Forecast System (GEFS).

The change will correct the bitmasks used in the GRIB files to
denote the boundaries of variables defined only over land and/or
ice. The change will affect the soil temperature and soil
moisture in the 0-10cm depth layer and the snow depth fields
only.

This change affects ensemble mean and spread products for the
0 to 192-hr forecast hours and then every 12 hours from 204 to
380 hours. In these three fields, the bitmasking results in no
data value when the grid point is over water. In the current
GEFS, some of the bitmasks have been inconsistent for these
three output products. With this change, the bitmask will now be
consistent across all products. Users may see some points
previously having missing values now have data, and vice versa.

This change does not affect any products available on NOAAPORT
or in AWIPS.

These ensemble mean and spread products are available on the
NCEP FTP server at:

ftp.ncep.noaa.gov/pub/data/nccf/com/gens/prod/gefs.YYYYMMDD

where YYYYMMDD is the year, month and day.  The files containing
these products are:

pgrb2a/geavg.tHHz.pgrb2afFF
pgrb2a/gespr.tHHz.pgrb2afFF
pgrb2alr/geavg.tHHz.pgrb2afFF.2
pgrb2alr/gespr.tHHz.pgrb2afFF.2

where HH is the model cycle and FF is the forecast hour.

Sample products with the new, consistent bitmasks are online at:

ftp://ftp.emc.ncep.noaa.gov/gmb/rwobus/avgspr

pgrb2a.2012022400.prod contains current GEFS output
pgrb2a.2012022400.test contains the product as it will be after
implementation.

For questions regarding these changes, please contact:

    Dingchen Hou
    NCEP/EMC Global Modeling Branch
    Camp Springs, Maryland
    301-763-8000 x7015
    dingchen.hou@xxxxxxxx
or
    Richard Wobus
    NCEP/Environmental Modeling Center
    Camp Springs, Maryland
    301-763-8000 x 7712
    Richard.Wobus@xxxxxxxx

NWS National Technical Implementation Notices are online at:

    http://www.nws.noaa.gov/os/notif.htm

$$