NOUS41 KWBC 291721 AAA



Technical Implementation Notice 14-15: Amended

National Weather Service Headquarters Washington DC

120 PM EDT Tue Jul 29 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:  Amended: Increasing Resolution in the National Digital

          Forecast Database (NDFD) Effective Tuesday,

          August 19, 2014


Amended to change the following:


1.    Exclude changes to resolution of eXtensible Markup

Language (XML) via Simple Object Access Protocol (SOAP)

and Representational State Transfer (REST)

2.    Include access to legacy CONUS grids at current resolution

after the implementation

3.    Note that preparatory work combining fine resolution files

in the experimental NDFD was completed on May 6, 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)


This implementation WILL NOT affect CONUS forecasts available

from NDFD in these standard methods:


- eXtensible Markup Language (XML) via Simple Object Access

Protocol (SOAP) and Representational State Transfer (REST),

which will remain at their current resolution


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

elements at fine resolution.


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:



Legacy CONUS grids at the current resolution will be made

available for at least 90 days after the operational

implementation at the following URLs:



Effective May 6, 2014 (per TIN 14-14), fine resolution element

grids were 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

were 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 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, MD 20910


For questions regarding this notice, please contact:


  Andy Horvitz

  NWS Office of Climate Water and Weather Services

  Silver Spring, MD 20910


Technical Implementation Notices specifically related to NDFD

are online at:


National Technical Implementation Notices are online at: