NOUS41 KWBC 151418
Technical Implementation Notice 11-11
Weather Service Headquarters
1018 AM EDT Fri Mar 25 2011
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
Other NWS Partners, Users and Employees
From: Timothy McClung
Science Plans Branch Chief
Office of Science and Technology
Subject: GFDL Hurricane Prediction System Changes:
Effective May 17, 2011
Effective Tuesday, May 17, 2011, 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:
- Upgrade Simplified Arakawa-Schubert (SAS) deep convection
parameterization to new version implemented in the NCEP
Global Forecast System (GFS)
- Modify the surface enthalpy exchange coefficient and
dissipative heating effect
coupled region in the Eastern Atlantic domain
region. The new overlap will be 25 degrees.
- Correct several bugs in the model.
In testing, these improvements resulted in an average reduction
of forecast error of about 20 percent in the Atlantic basin
for the 3 to 5 day forecast period for tests of storms from
the 2010 Atlantic hurricane season.
The following will be added to the GFDL model output GRIB files:
Model-predicted 10 meter winds will be outputted in addition
to the lowest model level 35 meter winds.
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 dissemination time.
There will be only a minor increase in product size.
ftp server at:
where xx is the model cycle
More details about the GFDL hurricane prediction system are available at:
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:
NWS National Technical Implementation Notices are online at: