[nws-changes] 20120511: gfdl hurricane prediction system chgs Fwd: ADMIN NOTICE NOUS41 KWBC

• To: nws-changes@xxxxxxxxxxxxxxxx
• Subject: [nws-changes] 20120511: gfdl hurricane prediction system chgs Fwd: ADMIN NOTICE NOUS41 KWBC
• From: Linda Miller <lmiller@xxxxxxxxxxxxxxxx>
• Date: Fri, 11 May 2012 19:15:53 -0600

-------- Original Message --------
Subject:        ADMIN NOTICE NOUS41 KWBC
Date:   Fri, 11 May 2012 12:47:48 -0600
From:   Unidata Local Data Manager <ldm@xxxxxxxxxxxxxxxx>
To:     ldmnotices@xxxxxxxxxxxxxxxx



253
NOUS41 KWBC 111847
PNSWSH

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
morris.bender@xxxxxxxx

Timothy Marchok
GFDL/NOAA
Princeton, NJ
Phone: 609-452-6534
timothy.marchok@xxxxxxxx

NWS National Technical Implementation Notices are online at:

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

$$