NOUS41 KWBC 171814

PNSWSH

Technical Implementation Notice 12-49

National Weather Service Headquarters, Washington, DC

213 PM EDT Wed Oct 17 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 Branch

Office of Science and Technology

Subject: Modifications to NARRE Products:

Effective November 20, 2012

Effective Tuesday, November 20, 2012, with the 1200 Universal

Coordinated Time (UTC) cycle, the National Centers for

Environmental Prediction (NCEP) will modify the output from the Time-Lagged North American Rapid Refresh Ensemble Forecast System (NARRE). The following changes will be made:

- The products will be encoded using Version 2 of GRIB Table 2 to correct the label on the reflectivity grids from upward long wave radiative flux >30 (ULWRF) to the correct name: reflectivity > 30dBz (REFC).

- The vertical level ID in the GRIB encoding (kpds6) of accumulated precipitation (APCP) in the probability files will be set to the correct value of 1. It is currently set to 255.

- An additional variable of a 1 inch (or 25.5 mm) threshold for the 3hr and 6hr accumulated precipitation probability will be added to the files based upon user’s requests.

NARRE products are currently disseminated at the following locations:

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/rap/prod/narre.YYYYMMDD/ensprod

http://www.ftp.ncep.noaa.gov/data/nccf/com/rap/prod/narre.YYYYMMDD/ensprod

A sample of NARRE datasets with the changes made is online at:

ftp://ftp.emc.ncep.noaa.gov/mmb/bzhou/NARRE/20120726

The Environmental Modeling Center (EMC) Mesoscale Modeling Branch (MMB) has a publicly available Website that can provide users more information concerning NCEP regional modeling systems at:

http://www.emc.ncep.noaa.gov/mmb/mesoscale.html

NCEP encourages users to ensure their decoders are flexible and are able to adequately handle changes in content, parameter fields changing order, changes in the scaling factor component within the Product Definition Section/Template of the GRIB files and 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 the scientific content of the modeling system please contact:

Geoff Dimego

NCEP/EMC

College Park, Maryland

email: Geoff.dimego@noaa.gov

or:

Binbin Zhou

NCEP/EMC

College Park, Maryland

email: binbin.zhou@noaa.gov

For questions regarding the dataflow aspects of these data sets please contact:

NCEP/NCO Dataflow Team

College Park, Maryland

Phone: 301-683-0567

email: ncep.list.pmb-dataflow@noaa.gov

National Technical Implementation Notices are online at:

http://www.weather.gov/os/notif.htm

$$