NOUS41 KWBC 161933 AAC

PNSWSH

Technical Implementation Notice 11-58, Amended

National Weather Service Headquarters Washington DC

330 PM EDT Mon Apr 16 2012

TO: National Weather Service Offices (NWS)

Federal Aviation Administration Customers (FAA)

Family of Services Subscribers (FOS)

Other Customers of NWS Aviation Forecasts

FROM: Cynthia Abelman

Chief, Aviation Services Branch

SUBJECT: Amended: Graphical Turbulence Guidance (GTG) Change
Effective May 1, 2012

NOTE: The following changes have no impact on NOAA

Weather Wire Service subscribers

Amended to set the implementation date for Tuesday May 1, 2012.

Users are cautioned that if a Critical Weather Day (CWD) designation is in effect on May 1, this implementation will be delayed until the conclusion of CWD. You can monitor the CWD status at the following webpage:

http://www.nco.ncep.noaa.gov/pmb/cwd/

See TIN 11-36, issued July 27, 2011, announcing the intention to replace the Rapid Update Cycle (RUC) model with the Rapid Refresh (RAP) model, and the Public Information Statement issued November 9, 2011, proposing to remove some RUC output products.

http://www.nws.noaa.gov/os/notification/tin11-36ruc.htm

Effective May 1, 2012, 1200 Coordinated Universal Time (UTC), the NWS Aviation Weather Center in Kansas City, MO, will update the GTG product in conjunction with the implementation of the RAP model. This change impacts users as follows:

1. Resolution of the grid spacing will increase from 20KM

to 13KM.

2. As a result of increased resolution, the parameter Grid

ID (PDS OCTET 7), internal to the GRIB file, will change

to 130. For more information, see

http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html

This change will affect the following WMO headers for GTG:

WMO FLIGHT

HEADER LEVEL

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

YVW*14 KKCI FL450

YVW*15 KKCI FL440

YVW*16 KKCI FL430

YVW*17 KKCI FL420

YVW*18 KKCI FL410

YVW*19 KKCI FL400

YVW*20 KKCI FL390

YVW*21 KKCI FL380

YVW*22 KKCI FL370

YVW*23 KKCI FL360

YVW*24 KKCI FL350

YVW*25 KKCI FL340

YVW*26 KKCI FL330

YVW*27 KKCI FL320

YVW*29 KKCI FL310

YVW*30 KKCI FL300

YVW*32 KKCI FL290

YVW*33 KKCI FL280

YVW*34 KKCI FL270

YVW*36 KKCI FL260

YVW*38 KKCI FL250

YVW*39 KKCI FL240

YVW*41 KKCI FL230

YVW*43 KKCI FL220

YVW*45 KKCI FL210

YVW*46 KKCI FL200

YVW*48 KKCI FL190

YVW*50 KKCI FL180

YVW*53 KKCI 170

YVW*55 KKCI 160

YVW*57 KKCI 150

YVW*60 KKCI 140

YVW*62 KKCI 130

YVW*65 KKCI 120

YVW*67 KKCI 110

YVW*70 KKCI 100

ZVW*50 KKCI Composite

WHERE * = A = 00 HOUR FORECAST

* = B = 01 HOUR FORECAST

* = C = 02 HOUR FORECAST

* = D = 03 HOUR FORECAST

* = G = 06 HOUR FORECAST

* = J = 09 HOUR FORECAST

* = M = 12 HOUR FORECAST

The GTG graphics are computer-generated four-dimensional forecasts of information related to the likelihood of encountering atmospheric turbulence.

The product provides forecasts for the 48 contiguous United States, much of Canada and Mexico, and their respective coastal waters at flight altitudes from 10,000 MSL to FL450 only; it does not provide forecasts from the surface to 10,000 ft. Users should also be aware that turbulence is a highly dynamic phenomenon and, in case of rapidly changing conditions, the product may not accurately convey a significant hazard. GTG may be used as a higher-resolution supplement to AIRMETs and SIGMETs, but not as a substitute for the turbulence information they provide. GTG-2 graphics are authorized for use as an unrestricted, supplementary weather product. The GTG-2 does not have the capability to be amended. See the definition of primary and supplementary weather products below.

GTG is produced automatically from the 13 KM Weather Research and Forecasting RAP model runs. GTG produces an Analysis, 1, 2, 3, 6, 9 and 12-hour Turbulence Forecast every hour in GRIB format. This product also provides a composite field representing the maximum turbulence value between 10,000 and 45,000 feet for each analysis and forecast.

The GTG graphics suite is automatically produced with no human modifications. Information on the graphics is determined from observational data, pilot weather reports, upper air soundings, satellite soundings, automated aircraft reports, and surface weather reports, all of which are integrated with computer model output.

Early to mid-May, 2012, GTG output in Gridded Binary (GRIB) format will be available through:

- NWS FTP servers at:

ftp://tgftp.nws.noaa.gov/SL.us008001/DC.avspt/DS.fipgb

- The Family of Services (FOS) High Resolution Data Service and

Server Access Service

- Satellite Broadcast Network (SBN) NOAAPORT channel

To obtain sample gridded GTG data, contact:

Robert Sallee

Senior Software Engineer - Aviation Weather Center

Kansas City, MO 64153

816-584-7256

robert.sallee@noaa.gov