NOUS41 KWBC 221230



Technical Implementation Notice 16-34

National Weather Service Headquarters Washington DC

830 AM EDT Wed Sep 22 2016


To:       Subscribers:

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners, Users and Employees


From:     Eli Jacks

          Chief, Forecast Services Division


Subject:  Addition of grids for the 0.25 inch (~6 mm)

          threshold of Experimental Day 4-7 Winter Weather

          Outlook as an experimental element in the National

          Digital Forecast Database (NDFD) for the CONUS

          effective October 11, 2016


Effective October 11, 2016, at 1930 Coordinated Universal Time

(UTC), NWS will add grids for the 0.25 inch (~6 mm) threshold of

the Experimental Day 4-7 Winter Weather Outlook to the National

Digital Forecast Database (NDFD) as an experimental element for

the Continental United States.


The Experimental Day 4-7 Winter Weather Outlook, produced by the

NWS National Centers for Environmental Prediction (NCEP) Weather

Prediction Center (WPC), is a forecast depicting the probability

of winter precipitation (snow/sleet) exceeding 0.25 inches (~6

mm) water equivalent over a 24-hour period (Valid Time 12z-12z).


The product is comprised of 4 separate grids containing the

forecast for Days 4, 5, 6 and 7. The product is updated daily at

approximately 0900 UTC and 1930 UTC.


More details on the Experimental Day 4-7 Winter Weather Outlook

product, as well as its technical description and scientific

basis, are available in the Product Description Document:


These experimental grids will be available from NDFD in the

following standard methods:


-Gridded Binary version 2 (GRIB2) files via Hypertext Transfer

Protocol (HTTP) and File Transfer Protocol (FTP)

-Extensible Markup Language (XML) via Simple Object Access

Protocol (SOAP)

-Graphics via Web browser


Users who pull NDFD elements in GRIB2 format via the

Internet may need to update their procedures and scripts to

access this new element. 


The new files will be available for download at the following

links effective October 11, 2016:


GRIB2 files:




Graphics and XML services for the experimental grids will become

available within 30 days of the experimental release of the

GRIB2 file into the NDFD.


NDFD online graphics:


XML SOAP service:


Information on accessing and using NDFD elements is online at:


Comments and feedback on these experimental elements are welcome

through March 31, 2017 at:


GRIB2 users:


Users of XML SOAP service:


NDFD online graphics:


For general questions regarding NDFD data, please email:


For technical questions regarding NDFD data please contact:


  David Ruth

  NWS/STI/Digital Forecast Services Branch

  National Weather Service Headquarters

  Silver Spring, Maryland 20910



For questions regarding this notice, please contact:


  James Nelson

  NWS/WPC/Development and Training Branch

  National Centers for Environmental Prediction

  College Park, MD 20740



Technical Implementation Notices (TIN) specifically related to

the NDFD are online at:


National TINs are online at: