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-------- Original Message --------
674
NOUS41 KWBC 281432
PNSWSH
Service Change Notice 13-25
National Weather Service Headquarters Washington DC
1033 AM EDT Thu Mar 28 2013
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
-NOAAPort
Other NWS partners and employees
From: Cynthia Abelman
Chief, Aviation Services Branch
Subject: Format Change for World Area Forecast System (WAFS)
Upper Air Forecasts Effective November 13, 2013.
Effective Wednesday, November 13, 2013, at 1800 Coordinated
Universal Time (UTC), the NWS will cease providing WAFS Global
Gridded Forecasts in the World Meteorological Organization (WMO)
GRIdded Binary 1 (GRIB1) code format. At that time, WAFS Global
Forecasts will only be available in WMO GRIB2 format.
This change is being implemented in accordance with the
International Civil Aviation Organization (ICAO) WAFS Operations
Group seventh meeting. This meeting made GRIB2 WAFS Global
Gridded Forecasts operationally available and conforms to ICAO
Annex 3. All users of WAFS Upper Air Forecasts in GRIB1 format
are urged to migrate to WAFS Upper Air Forecasts in GRIB2 format
at the earliest opportunity.
GRIB2 is a binary format developed by the WMO containing gridded
data. GRIB2 was approved for experimental use by the WMO/CBS in
1998 and for operational use in 2000. GRIB2 addressed the GRIB1
problem of tables being full and the format inability to expand
or extend the tables. GRIB2 introduced a more comprehensive
parameter identification system and expanded use of templates.
There are differences in technical encoding between GRIB1 and
GRIB2. There are five major differences, from the meteorological
and operational perspective, between the two formats are:
1 GRIB2 is a regular grid with 1.25 X 1.25 degree (~140KM X 140
KM at the equator) resolution. GRIB1 has the longitudinal
points on the grid "thinned" as the polar regions are
approached.
2 GRIB2 bulletins contain data covering the entire globe for each
level and each parameter in every bulletin. GRIB1 has separate
bulletins for each "octant" of every level/parameter
combination.
3 GRIB2 data is compressed using the JPEG2000 standard.
Appropriate JPEG2000 decompression libraries will be necessary.
4 GRIB2 has a temporal resolution of 3 hours, from T+06 to T+36
inclusive. GRIB1 has a temporal resolution of 6 hours (T+06
to T+36 inclusive).
5 GRIB2 has additional levels close to the normal cruise of level
of airliners.
Guidance on the WAFS Global Gridded Forecasts in WMO GRIB2 Format
is available on the WAFS Operations Group Website:
http://www.icao.int/safety/meteorology/WAFSOPSG/Pages/GuidanceMat
erial.aspx
In support of the WAFS, NWSs World Area Forecast Center
Washington provides global gridded forecasts of upper wind and
temperature data covering Flight Levels FL050-530, tropopause
heights and temperature, and maximum wind (height, speed,
direction). This data is based on output from the Global Forecast
System Numerical Weather Model. The data can be used in flight
planning systems to optimize flights routes or to generate a
range of charts, such and wind and temperature charts, cross
sections, etc.
The aforementioned gridded products are produced four times
daily, for T+06 to T+36 hour time steps, and are available in
GRIB2 format on the WAFS Internet File System (WIFS). WIFS is
available to registered users at:
http://www.aviationweather.gov/wifs/
For technical questions and support in registering a user account
at the WIFS Website or downloading and accessing the GRIB2 data,
contact:
Ryan Solomon
Aviation Weather Center
Kansas City, MO 64153
816-584-72048
ryan.l.Solomon@xxxxxxxx
If you have any questions about this change, or the WAFS Global
Grids data set, please contact:
Matt Strahan
Chief, International Operations Branch
Aviation Weather Center/WAFC Washington
Kansas City, MO 64153
816-584-7204
matt.strahan@xxxxxxxx
National Technical Implementation Notices are online at:
http://www.nws.noaa.gov/om/notif.htm
$$
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