NOUS41 KWBC 271940
PNSWSH

Technical Implementation Notice 15-50
National Weather Service Headquarters Washington DC
337 PM EDT Tue Nov 27 2015

To:	  Subscribers:
	  -Family of Services
	  -NOAA Weather Wire Service
	  -Emergency Managers Weather Information Network
	  -NOAAPORT
	  -Other NWS Partners, Users and Employees

From:	  Tim McClung
	  Portfolio Manager
	  Office of Science and Technology Integration

Subject:  Implementation of experimental National Blend
	  of Models guidance for the CONUS effective
	  December 15, 2015

On or about Tuesday, December 15, 2015, beginning with the
1200 Coordinated Universal Time (UTC) model run, the NWS
Meteorological Development Laboratory (MDL) will implement
experimental National Blend of Models (NBM) guidance for the
CONUS. Guidance will include blends of deterministic and
ensemble mean-based model grids for the following weather
elements:

    1. Sky cover (3-hourly)
    2. 10-m wind direction (3-hourly)
    3. 10-m wind speed (3-hourly)
    4. 2-m temperature (3-hourly)
    5. 2-m dewpoint temperature (3-hourly)
    6. Daytime maximum temperature
    7. Nighttime minimum temperature
    8. 2-m relative humidity (3-hourly)
    9. 2-m apparent temperature (3-hourly)
    10. 10-m wind gust (3-hourly)

These products will be produced on a 2.5-km Lambert Conformal
grid over the CONUS with dimensions NX=2145 and NY=1597. This
change represents an expansion to the north by 220 grid lengths
compared to the current National Digital Forecast Database
(NDFD) CONUS grid to provide coverage for the entire Northwest
River Forecast Center basin. Guidance will be available for the
0000 and 1200 UTC model cycles for projections from 6 hours to
192 hours in advance. These products will be disseminated on the
Satellite Broadcast Network (SBN), NOAAPORT and the NWS ftp
server in GRIB2 format.

These NBM products for the CONUS will be available in GRIB2
format on or about Tuesday, December 15, 2015, in the
experimental area of the National Digital Guidance Database
(NDGD) on the NWS ftp server at:

ftp://tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndgd/GT.b
lend/AR.conus/

This directory will contain subdirectories for each valid period
as follows:

    VP.001/	  Day 1
    VP.002/	  Day 2
    VP.003/	  Day 3
    VP.004/	  Day 4
    VP.005-007/  Days 5-7
    VP.008-450/  Days 8 and beyond

Each element-specific GRIB2 file will reside in the appropriate
valid period subdirectory and contain a WMO superheader and
individual headers. A listing of the GRIB2 file names for each
element is given in Table 1 below. WMO superheaders for the NBM
CONUS products are given in Table 2.

Table 1: GRIB2 file names for the NBM elements

These files will reside in the appropriate valid period
subdirectory on tgftp

  GRIB2 FILE NAME   ELEMENT
  ---------------   -----------------------------
  ds.skymean.bin    Sky cover
  ds.wdirmean.bin   Wind direction
  ds.wspdmean.bin   Wind speed
  ds.tempmean.bin   2-m temperature
  ds.tdmean.bin     2-m dewpoint temperature
  ds.maxtmean.bin   Daytime maximum temperature
  ds.mintmean.bin   Nighttime minimum temperature
  ds.rhmean.bin     2-m relative humidity
  ds.apptmean.bin   2-m apparent temperature
  ds.wgustmean.bin  Wind gust

Table 2: WMO superheaders for each CONUS NBM element

Listed below are representations of the superheaders where ii=98
for day 1, ii=97 for day 2, ii=96 for day 3, ii=95 for day 4,
ii=94 for days 5-7, and ii=93 for days 8 and beyond.

  WMO SUPERHEADER   ELEMENT
  ---------------   -----------------------------
  LAAZii KWEA	     Sky cover
  LBAZii KWEA	     Wind direction
  LCAZii KWEA	     Wind speed
  LEAZii KWEA	     2-m temperature
  LFAZii KWEA	     2-m dewpoint temperature
  LGAZii KWEA	     Daytime maximum temperature
  LHAZii KWEA	     Nighttime minimum temperature
  LRAZii KWEA	     2-m relative humidity
  LTAZii KWEA	     2-m apparent temperature
  LWAZii KWEA	     Wind gust


Beginning approximately 1 month prior to the implementation
date, users may find parallel data for download on the
Operational Model Archive and Distribution System (NOMADS) at:

http://para.nomads.ncep.noaa.gov/pub/data/nccf/noaaport/blend/

For questions regarding the implementation of NBM guidance for
the CONUS, please contact:

 David Myrick
 MDL/Silver Spring, Maryland
 301-427-9455
 David.Myrick@noaa.gov

NWS National TINs are online at:

 http://www.weather.gov/os/notif.htm