NOUS41 KWBC 111847 AAA
Technical Implementation Notice 12-18, Amended
National
Weather Service Headquarters Washington DC
248 PM EDT Fri May 11 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
Science Plans Branch Chief
Office of Science and Technology
Subject: Amended: GFDL Hurricane Prediction System Changes:
Effective May 29, 2012
Amended to reschedule the implementation for Tuesday, May
29, 2012.
Effective
on or about Tuesday, May 29, 2012, beginning with the 1200
Coordinated Universal Time (UTC)
run, the National Centers for Environmental Prediction (NCEP) will upgrade the Geophysical Fluid
Dynamics Laboratory (GFDL) Hurricane Prediction System. The scientific changes
to the model include the following:
- Bug
fix in PBL scheme from 2003 implementation
- Bug
fix in Simplified Arakawa-Schubert (SAS) deep convection
from 2010
implementation
- Implementation of GFS Shallow Convection
-
Modification of the surface exchange coefficient (ch,
cd)
- Modifications to GFS PBL scheme and momentum
mixing term in
SAS deep
convection
- Detrained micro-physics generated in SAS and
passed to
Ferrier
micro-physics scheme
-
Reduced specification of storm size for larger storms
In
tests of storms from the 2011 Atlantic hurricane season, these improvements
resulted in an average reduction of track forecast error of about 12 percent in
the 2 to 5 day forecast time periods.
The
average reduction in intensity errors averaged nearly 20 percent in the
Atlantic basin during the same forecast time periods for the 2011 Atlantic
hurricane season, primarily through elimination of the large positive intensity
bias.
Product
Changes:
The
GFDL hurricane model GRIB products are disseminated via the NCEP and NWS FTP
servers and are not available on NOAAPORT or AWIPS. These changes will result in no change in product content
or dissemination time.
The
GFDL data is available on the NWS ftp server at:
ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ghm_CY.xx where xx is the model cycle,
and at the NCEP servers at:
www.ftp.ncep.noaa.gov/data/nccf/com/hur/prod/hur.YYYYMMDDHH
and
ftp.ncep.noaa.gov/pub/data/nccf/com/hur/prod/hur.YYYYMMDDHH
where YYYY is year, MM is month, DD is day, and HH is model
cycle.
More
details about the GFDL hurricane prediction system are online at:
http://www.gfdl.noaa.gov/operational-hurricane-forecasting
NCEP encourages all users to ensure their
decoders are flexible and are able to adequately handle changes in content
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
implementations.
For
questions regarding these model changes, please contact:
Morris
Bender
gfdl/noaa
Princeton, nj
Phone:
609-452-6559
Timothy Marchok
gfdl/noaa
Princeton,
NJ
Phone:
609-452-6534
NWS
National Technical Implementation Notices are online at:
http://www.nws.noaa.gov/os/notif.htm
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