NOUS41 KWBC 271937



Technical Implementation Notice 15-50

National Weather Service Headquarters Washington DC

337 PM EDT Tue Oct 27 2015


To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          -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



     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:


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



   ---------------   -----------------------------

   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.



   ---------------   -----------------------------

   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:


For questions regarding the implementation of NBM guidance for

the CONUS, please contact:


  David Myrick

  MDL/Silver Spring, Maryland



NWS National TINs are online at: