NOUS41 KWBC 152014 AAC

PNSWSH

 

Technical Implementation Notice 11-35, Amended

National Weather Service Headquarters Washington DC

415 PM EST Thu Nov 15 2012

 

To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network

          -NOAAPORT  

          Other NWS partners and NWS employees

 

From:     Tim McClung

          Chief, Science Plans Branch

          Office of Science and Technology

 

Subject:  Amended Changes and Additions to NAM-DNG Products,

          Including Distribution of New High-Resolution DNG

          Effective Date of NOAAPORT Activation: December 4,

          2012.

 

Amended to set the implementation date to add these products to

NOAAPORT to Tuesday, December 4, 2012. 

 

The modifications to the current NAM DNG, as part of the upgrade

of the NAM prediction system, were implemented when the NAM

upgrade was completed on October 18, 2011. This amended TIN

covers the addition of these products to NOAAPORT.  No changes

are being made at this time to the content of the products. 

Much of what follows is directly from the original phrasing of

TIN 11-35, with some minor wording changes.

 

Effective with the upgrade of the North American Mesoscale (NAM)

prediction system, and inclusion of high resolution nests (see

TIN 11-16), the National Centers for Environmental Prediction

(NCEP) will modify and enhance the suite of NAM Downscaled

Numerical Guidance (NAM-DNG).

 

The current NAM-DNG products are distributed to the Continental

U.S. (CONUS), Alaska, Hawaii and Puerto Rico out to 84 hours

over the AWIPS SBN/NOAAPORT and are available on the NCEP

server. The new NAM nests are run only to 60 hours but are run

at resolutions much closer to the National Digital Forecast

Database (NDFD) forecast grids used in the DNG than the 12km

NAM, now called the parent grid. 

 

After the modification of existing NAM-DNG is implemented, as

stated in TIN 11-16, the first 60 hours (54 hours) of the

current 0000 and 1200 UTC (0600 and 1800 UTC), NAM-DNG will come

from the NAM nests instead of from the 12km NAM parent.

 

--CONUS: 4km NAM nest will feed 5km NAM-DNG 

--Alaska: 6km NAM nest will feed 5.9km NAM-DNG 

--Hawaii, Puerto Rico: 3km NAM nests will feed 2.5km NAM-DNG 

 

In this way, only slight downscaling (or upscaling in the case

of CONUS) is required. Currently, all systems downscale from

12km.

 

After the change, there may be some unavoidable amount of

discontinuity between the NAM-nest-based 60-hr (54 hr for 0600

and 1800 UTC) and the NAM-parent-based 63-hr (57 hr for 0600 and

1800 UTC) guidance. These modifications will occur when the NAM

upgrade, detailed in TIN 11-16 linked below, is implemented

later this summer.

 

www.weather.gov/os/notification/tin11-16nam_changes_aad.htm

 

The enhancement of NAM-DNG will come from the addition of 

NAM-DNG for CONUS and Alaska at double the present NDFD

resolution through the 60 hours covered by the NAM nests.

 

For CONUS, the 4km NAM nest will feed a 2.5km NAM-DNG. For

Alaska, the 6km NAM nest will feed a 3km NAM-DNG. Output will be

made available every 3 hours from 0-60 hours for all 4 NAM

cycles.

 

These new high-resolution NAM-DNG products will be available

on the NCEP server when the NAM upgrade is implemented. In

addition, simulated composite reflectivity will be added to

output for both the modified and enhanced NAM-DNG. The new high-

resolution NAM-DNG products will be made available on NOAAPORT

on Tuesday December 4, 2012.

 

The grids listed below in Table 1 for CONUS and Table 2 for

Alaska will be available at double NDFD resolutions.

  

NCEP will remove the coarser 5km CONUS and 5.9km Alaska NAM-DNG

products from NOAAPORT and all other distribution methods once

sufficient time has passed to allow software upgrades.  A

separate announcement will be sent before removing these

products.

 

Table 1:  NAM-DNG products available over CONUS at 

2.5km resolution and their associated WMO headers

  

WMO Header       NAM-DNG Parameter

[L|M]AJ*** KWBE  Dewpoint temperature

[L|M]AJ*** KWBE  Cloud Cover

[L|M]AJ*** KWBE  Wind Speed

[L|M]AJ*** KWBE  Wind Direction

[L|M]AJ*** KWBE  Wind Gust Speed

[L|M]DJ*** KWBE  Probability of Precipitation (3, 6 & 12 hourly)

[L|M]EJ*** KWBE  Total Precipitation (3, 6 & 12 hourly)

[L|M]HJ*** KWBE  Boundary layer height or wet bulb zero height

[L|M]KJ*** KWBE  Visibility 

[L|M]RJ*** KWBE  Minimum/Maximum relative humidity(3 & 12

hourly)

[L|M]SJ*** KWBE  Snow depth (3 & 6 hourly)

[L|M]TJ*** KWBE  Temperature

[L|M]TJ*** KWBE  Minimum/Maximum temperature (3 & 12 hourly)

[L|M]UJ*** KWBE  U component of wind

[L|M]VJ*** KWBE  V component of wind

[L|M]ZJ*** KWBE  Simulated composite reflectivity

 

 

Table 2:  NAM-DNG products available over Alaska at 3km

resolution and their associated WMO headers

  

WMO Header     NAM-DNG Parameter

[L|M]AK*** KWBE  Dewpoint temperature

[L|M]AK*** KWBE  Cloud Cover

[L|M]AK*** KWBE  Wind Speed

[L|M]AK*** KWBE  Wind Direction

[L|M]AK*** KWBE  Wind Gust Speed

[L|M]DK*** KWBE  Probability of Precipitation (3, 6 & 12 hourly)

[L|M]EK*** KWBE  Total Precipitation (3, 6 & 12 hourly)

[L|M]HK*** KWBE  Boundary layer height or wet bulb zero height

[L|M]KK*** KWBE  Visibility 

[L|M]RK*** KWBE  Minimum/Maximum relative humidity(3 & 12

hourly)

[L|M]SK*** KWBE  Snow depth (3 & 6 hourly)

[L|M]TK*** KWBE  Temperature

[L|M]TK*** KWBE  Minimum/Maximum temperature (3 and 12 hourly)

[L|M]UK*** KWBE  U component of wind

[L|M]VK*** KWBE  V component of wind

[L|M]ZK*** KWBE  simulated composite reflectivity

 

 

A Website outlining all of the NAM-DNG WMO headers is online at: 

 

www.nco.ncep.noaa.gov/pmb/changes/nam_dng_wmoheaders.shtml

 

The NAM-DNG grids are made available from the NCEP server at:

 

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nam/prod/

 

or

 

http://www.ftp.ncep.noaa.gov/data/nccf/com/nam/prod

 

There are files for the four nests: smartconus, smartak, smarthi

and smartpr followed by the two-digit forecast hour.  The CONUS

files will be named smartconus for the 5km and smartconus2p5 for

the 2.5km.  Similarly Alaska files will be smartak for the 6km

grids and smartak3 for the 3km grids. 

 

For questions regarding the NAM-DNG, please contact:

 

  Geoff DiMego

  NCEP/Environmental Modeling Center

  College Park, Maryland

  301-683-3764

  geoff.dimego@noaa.gov

or 

  Geoff Manikin

  NCEP/Environmental Modeling Center

  College Park, Maryland

  301-683-3695

  geoffrey.manikin@noaa.gov

 

For questions regarding the dataflow aspects of these data

sets please contact:

 

  Rebecca Cosgrove

  NCEP/NCO Dataflow Team

  College Park, Maryland

  301-683-0567

  ncep.list.pmb-dataflow@noaa.gov

 

National Technical Implementation Notices are online at:

 

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

 

$$