NOUS41 KWBC 011917



Technical Implementation Notice 14-15

National Weather Service Headquarters Washington DC

320 PM EDT Tue Apr 1 2014


To:       Subscribers:

          - Family of Services

          - NOAA Weather Wire Service

          - Emergency Managers Weather Information Network

          - NOAAPORT

          Other NWS partners and NWS employees


From:     Eli Jacks

          Chief, Fire and Public Weather Services Branch


Subject:  Increasing Resolution in the National Digital Forecast

          Database (NDFD) Effective Tuesday, August 19, 2014


Effective Tuesday, August 19, 2014, at 1400 Coordinated Universal

Time (UTC), the NWS will transition the spatial and temporal

resolution in the NDFD from experimental to operational status. 

After this transition, the operational NDFD will be available at

2.5km spatial resolution for all forecast times and at 1 hour

temporal resolution for the first 36 hours from NDFD issuance

time. These are the finest spatial and temporal resolutions at

which Weather Forecast Offices in the Conterminous United States

(CONUS) provide forecasts. Forecasts from NWS offices and centers

employing coarser resolutions will be mapped onto the finer

resolution NDFD grid.


This change will affect files containing data for the entire

CONUS, but will not affect Alaska, Hawaii, Guam, Puerto Rico and

the Virgin Islands, or the pre-defined 16 CONUS subsectors which

will remain at their current operational resolutions.


Specifications for the 2.5km NDFD CONUS grid can be viewed at the

following URL:


This implementation will affect CONUS forecasts available from

NDFD in these 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) and Representational State Transfer (REST)


Users who pull NDFD elements in GRIB2 format, either via the

internet or via the Family of Services server access service, may

need to update their procedures and scripts to access these new



To access experimental fine resolution grids before the

operational implementation, use the following URLs:



To access fine resolution grids after 1400 UTC on August 19,

2014, use the following URLs. These URL will not be active before

operational implementation:



Element grids will be combined into one file for day 1 through

day 3, and a second file for day 4 through day 7, using the same

WMO headers currently on operational NDFD grids. Grids for

selected elements will be more tightly packed in GRIB2 format

with both decimal and binary scaling applied.  GRIB2 encoding

characteristics for each NDFD element can be viewed at the

following URL:


To view NDFD grids for the CONUS at full resolution, use the

experimental NDFD map viewer at the following URL:


General information on accessing and using NDFD elements is

online at:


If August 19, 2014, is a critical weather day, this

implementation may be postponed. Users will be notified of that

decision via another Technical Implementation Notice as far in

advance as possible.


For general questions regarding NDFD data, please email:


For technical questions regarding NDFD data, please contact:


  David Ruth

  Chief, Mesoscale Prediction Branch

  NOAA/NWS Office of Science and Technology

  Silver Spring, Maryland 20910


For questions regarding this notice, please contact:


  Andy Horvitz

  National Weather Service

  Office of Climate Water and Weather Services

  Silver Spring, Maryland 20910


Technical Implementation Notices specifically related to NDFD are

online at:


National Technical Implementation Notices are online at: