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NOUS41 KWBC 291721

Technical Implementation Notice 14-15: Amended
National Weather Service Headquarters Washington DC
120 PM EDT Tue Jul 30 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:

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