NOUS41 KWBC 231822
PNSWSH
 
Public Information Notice
National Weather Service Headquarters Washington DC
120 PM EDT Thu Aug 23 2012
 
To:       Subscribers:
          - Family of Services
          - NOAA Weather Wire Service
          - Emergency Managers Weather Information Network
          - NOAAPORT
          Other NWS partners and NWS employees
 
From:     Jason Tuell 
          Chief, Meteorological Services Division
 
Subject:  Seeking Comments on Increasing the Resolution in the
          National Digital Forecast Database (NDFD) Effective
          August 28, 2012
 
Effective Tuesday, August 28, 2012, at 10:00 am EDT, 1400 
Coordinated Universal Time (UTC), the NDFD spatial resolution 
will become available in experimental status at 2.5km resolution 
for all forecast times. The NDFD temporal resolution will be 
available in experimental status at 1 hour 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 which contain data for the entire 
CONUS, but will not include Alaska, Hawaii, Guam, Puerto Rico 
and the Virgin Islands, or the 16 CONUS subsectors which will 
remain at their current operational resolutions. 
 
Specifications for operational and experimental NDFD grids 
can be viewed at the following URL:
 
http://graphical.weather.gov/docs/ndfdSRS.htm
 
Operational NDFD data will continue to be provided in parallel at 
current spatial and temporal resolutions throughout the experimental 
120 day period. Experimental fine resolution forecasts will be updated 
approximately 15 minutes after operational NDFD forecasts.  NDFD 
graphics and SOAP/REST/XML services will continue to be provided from 
operational NDFD grids during the experimental 120 day period.
 
To access experimental fine resolution grids, go to:
 
ftp://tgftp.nws.noaa.gov/sl.us008001/st.expr/df.gr2/dc.ndfd/ar.conus/
or
http://weather.noaa.gov/pub/sl.us008001/st.expr/df.gr2/dc.ndfd/ar.conus
 
Experimental grids for forecast days 1 through 3 will be provided in 
individual files for each day to limit file sizes.  Experimental 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:
 
http://graphical.weather.gov/docs/grib_design.html#element_encoding_lo
 
File structures and GRIB2 packing for operational NDFD files will remain 
unchanged during the experimental period. Experimental Ice Accumulation 
and daily Maximum and Minimum Relative Humidity grids will also remain 
unchanged, i.e., stay at 5km resolution.
 
WMO headers and file structures for current operational and experimental 
NDFD files can be viewed at:
 
http://www.nws.noaa.gov/ndfd/resources/NDFDelem_current.xls
 
WMO headers and files structure for the new experimental fine resolution 
files can be viewed at:
 
http://www.nws.noaa.gov/ndfd/resources/NDFDelem_fullres.xls
 
At the conclusion of the 120 day period, NWS will evaluate any comments 
and decide whether to proceed with operational implementation for the 
entire CONUS. Current operational resolutions will continue for Alaska, 
Hawaii, Guam, Puerto Rico and the Virgin Islands, and the 16 CONUS subsectors.
 
The NWS will accept comments and feedback on the increase in resolution 
during the experimental period through at least December 31, 2012.  
The survey link is online at:
 
http://www.nws.noaa.gov/survey/nws-survey.php?code=ndfd-grids25
 
General information on accessing and using NDFD elements is online at:
 
http://ndfd.weather.gov/technical.htm
 
For general questions regarding NDFD data, please email:
 
  nws.ndfd@noaa.gov
 
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
  David.Ruth@noaa.gov
 
For questions regarding this notice, please contact:
 
  Andy Horvitz
  National Weather Service
  Office of Climate Water and Weather Services
  Silver Spring, Maryland 20910
  Andy.Horvitz@noaa.gov
 
Technical Implementation Notices specifically related to NDFD are 
online at: 
 
  http://www.weather.gov/ndfd/tins.htm
 
National Public Information Notices are online at:  
 
  http://www.weather.gov/os/notif.htm
 
 
$$