NOUS41 KWBC 071143 AAB

PNSWSH

Technical Implementation Notice 11-35, Amended

National Weather Service Headquarters Washington DC

743 AM EDT Fri Oct 7 2011

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: Postponed

Amended to delay the addition of the new NAM DNG products to the SBN/NOAAPORT until further notice due to the need to network issues detected following the NOAAPORT/Satellite Broadcast Network (SBN) expansion and also to upgrade hardware storage and routing systems at the NWS Telecommunication Gateway (NWSTG). The modifications to the current NAM DNG, as part of the upgrade of the NAM prediction system, will proceed when the NAM upgrade is implemented in mid-October.

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, as stated in TIN11-16, 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 TIN11-16 linked below, is implemented later this summer.

www.weather.gov/os/notification/tin11-16nam_changes_aaa.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 once issues with the SBN expansion and at the TOC have been resolved. This TIN will be amended to reflect that activation date once it has been set.

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/

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.