NOUS41 KWBC 181940

PNSWSH

Technical Implementation Notice 11-14

National Weather Service Headquarters Washington DC

340 PM EDT Mon Apr 18 2011

To: Subscribers:

-Family of Services

-NOAA Weather Wire Service

-Emergency Managers Weather Information Network

-NOAAPORT

Other NWS Partners, Users and Employees

From: Tim McClung

Science Plans Branch Chief

Office of Science and Technology

Subject: Climate Forecast System (CFS) Change

Effective July 5, 2011, beginning with the 1200 Coordinated

Universal Time (UTC) run, the National Centers for Environmental Prediction (NCEP) will change the output grid of all of the nine(9) parameters in two (2) files from the Data Assimilation cycle of the Climate Forecast System (CDAS1) from 0.5x0.5 degree latitude-longitude to a 27 km Gaussian Grid (1760x880).

The nine (9) parameters that will be affected in each of the two (2) files are:

CWATclm - atmospheric column cloud water [kg/m2]

HGThlev1 - hybrid level 1 geopotential height [gpm]

PRESsfc - surface pressure [Pa]

PWATclm - atmospheric column precipitable water [kg/m2]

SPFHhlev1 - hybrid level 1 specific humidity [kg/kg]

TMPhlev1 - hybrid level 1 temperature [K]

UGRDhlev1 - hybrid level 1 u wind [m/s]

VGRDhlev1 - hybrid level 1 v wind [m/s]

The CDAS1 output files are available on the NCEP server at:

http://www.ftp.ncep.noaa.gov/data/nccf/com/cfs/prod/

and on NOMADS at:

http://nomads.ncep.noaa.gov/pub/data/nccf/com/cfs/prod/

The grid change will occur in the following two (2) files only:

cdas1.txxz.splgrbanl.grib2

cdas1.txxz.splgrbf06.grib2

where xx is 00, 06, 12, 18.

A set of test files is available at:

http://cfs.ncep.noaa.gov/pub/raid0/cfsv2/sample.spl.new

There will be no changes in the delivery time of CFS products.

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 changes, please contact:

Suranjana Saha

NCEP/EMC, Global Climate and Weather Modeling Branch

Camp Springs, Maryland

301-763-8000 x 7052

Suranjana.Saha@noaa.gov

John H. Ward

NCEP/EMC, Global Climate and Weather Modeling Branch

Camp Springs, Maryland

301-763-8000 x 7185

John.Ward@noaa.gov

For questions regarding the dataflow aspects of these datasets,