NOUS41 KWBC 041137 AAB

PNSWSH      

 

Technical Implementation Notice 13-50 Amended

National Weather Service Headquarters Washington DC

737 AM EDT Tue Apr 1 2014

 

To:      Subscribers:

         - Family of Services

         - NOAA Weather Wire Service

         - Emergency Managers Weather Information Network

         - NOAAPORT

         Other NWS partners and NWS employees

 

From:    Tim McClung

         Science Plans Branch Chief

         Office of Science and Technology

 

Subject: Amended: Changes to the Localized Aviation Model Output

         Statistics Program (LAMP) Products and addition

         of Convection Guidance and upgrade to Lightning

         Guidance: Effective April 8, 2014

 

This notice is being amended to postpone the implementation until

April 8, 2014, to allow time to correct a problem found with the

BUFR data in testing.

 

Beginning on or about Tuesday, April 8, 2014, beginning with the

1600 Coordinated Universal Time (UTC), the 2.5 km LAMP convection

and lightning gridded guidance in GRIB2 format will be available

in operational NDGD in these locations:

 

ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndgd/GT.glmp/AR.conus/VP.001-003/

 

http://weather.noaa.gov/pub/SL.us008001/ST.opnl/DF.gr2/DC.ndgd/GT.glmp/AR.conus/VP.001-003/

 

with these file names:

 

- LAMP Lightning Probabilities, on a 2.5 km grid: ds.plt02.bin

- LAMP Forecast Potential (no/low/medium/high) of lightning

  occurring, on a 2.5 km grid:  ds.olt02.bin

- LAMP Convection Probabilities, on a 2.5 km grid: ds.pcv02.bin

- LAMP Forecast Potential (no/low/medium/high) of convection

  occurring, on a 2.5 km grid:  ds.ocv02.bin 

 

The 2.5km guidance replaces the 5 km guidance.  Therefore, the

following 5 km files will be removed: 

 

- Lightning Probabilities in a 2-hr period, on a 5 km

  grid: ds.pts02.bin

- Thunderstorm Occurrence (Yes/No) in a 2-hr period, on a 5 km

  grid: ds.ots02.bin

 

from this directory:

 

ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndgd/GT.lampgfs/AR.conus

 

Note that the 5 km lightning guidance will still be available on

NOAAPort and the Satellite Broadcast Network until the time when

AWIPS can be modified to use the 2.5 km lightning guidance.

 

The LAMP 2.5 km convection and lightning grids are being produced

experimentally, and on the effective date, will become

operational. At that time, the decimal scaling in the GRIB2

messages containing probabilistic guidance will change from 

1 to 0.

 

The original notice, with revised date information, is below:

 

Effective on or about Tuesday, April 8, 2014, beginning with the

1600 Coordinated Universal Time (UTC) run, NWS will change the

LAMP guidance to add convection and upgrade the lightning

product.

 

On September 16, 2013, NWS solicited comments through November

15, 2013, regarding these changes:

 

http://www.nws.noaa.gov/os/notification/pnslampcnvltg.txt

 

After the comment period ended, an error was discovered in the

calculation of a lightning-based predictor associated with the

guidance. The error involved a small discrepancy in the timing of

the incorporated lightning strikes. A correction was implemented

Monday, December 23, 2013. In addition, a web page has been

posted to show the previous and corrected guidance, which

illustrates the effect of the correction for three cases:

 

http://www.nws.noaa.gov/mdl/gfslamp/lmpltgfix.php

 

Given this correction, NWS extended the comment period for these

products to January 16, 2014.

 

The LAMP convection and lightning forecast guidance consists of

probability forecasts and categorical forecasts (referred to as

"potential") in 20-km grid boxes for 2-h periods in the 3-to 25-h

range over the CONUS. Convection in a grid box is defined as the

occurrence of either radar reflectivity of greater than or equal

to 40 dBZ or at least one cloud-to-ground (CTG) lightning strike

or both during the 2-h valid period. Lightning occurrence in a

grid box is defined as at least one CTG lightning strike during

the 2-h valid period. The categorical LAMP convection and

lightning forecasts consist of four objectively defined potential

categories consisting of no, low, medium and high.

 

The experimental LAMP convection and lightning guidance contains

guidance on a 2.5 km Lambert Conformal grid covering the same

expanse as the National Digital Forecast Database (NDFD) CONUS

grid. Grids are generated hourly.

 

The proposed LAMP convection guidance is a new product, while the

upgraded LAMP lightning product is proposed to replace the

current LAMP thunderstorm guidance. The name of the latter will

change from thunderstorm to lightning, and the resolution will

change from 5 km to 2.5 km. In addition to the 2.5 km LAMP

lightning grids, corresponding grids will be produced for the

current 5 km grid. The four category product will be converted to

a Yes/No categorical product to support users who prefer to

maintain the content/format of the current lightning product.

 

Users can find more information about these products, as well as

links to the experimental data and images, at:

 

http://www.nws.noaa.gov/mdl/gfslamp/docs/cnvltg_info.php

 

With this change, the LAMP text bulletin (AWIPS PIL of LAV) will

change accordingly. The LAMP lightning probabilities and the four

category guidance (interpolated to stations) will replace the

current thunderstorm probabilities and two category guidance,

respectively. Also, NWS will add the LAMP convection

probabilities and four category guidance interpolated to

stations. An example of the current LAMP bulletin as compared to

the proposed LAMP bulletin is online:

 

http://www.nws.noaa.gov/mdl/gfslamp/docs/lavtxtdiff.php

 

The format of the new lightning guidance will look the same as

the format of the current thunderstorm guidance in the BUFR files

to support users who depend on this data and format. The

Convection Guidance will be added to the BUFR file at a later

time, and will be announced via a Technical Implementation

Notice. 

 

Users are encouraged to provide feedback on these experimental

products via a survey/comment form available at:

 

http://www.nws.noaa.gov/survey/nws-survey.php?code=LCULG

 

NWS made a final decision to approve implementation of these

proposed products in March 2014. This guidance will be

implemented on Tuesday, April 8, 2014, at 1600 UTC and

disseminated on the Satellite Broadcast Network (SBN), NOAAPort

and the NWS FTP server.

 

A web page outlining the LAMP products and the NWS server

directory and file structure can be found online at:

 

http://www.nws.noaa.gov/mdl/gfslamp/docs/NWS_tgftp_server_201403.shtml

 

The communication identifiers for the BUFR products, ASCII

products, and GRIB2 products are shown below in Tables 1-3.  A

complete list of gridded LAMP WMO headings is at:

 

http://www.nws.noaa.gov/mdl/gfslamp/docs/lampheaders_201403.pdf

 

Table 1: Communication Identifiers for the GFS-Based LAMP

Products in BUFR format 

 

Listed below are the WMO headings. These headings have not

changed.

 

WMO HEADING     REGION

-----------     ------

JSMF10 KWNO     LAMP BUFR PACIFIC REGION

JSMF11 KWNO     LAMP BUFR NORTHEAST REGION

JSMF12 KWNO     LAMP BUFR SOUTHEAST REGION

JSMF13 KWNO     LAMP BUFR NORTH CENTRAL REGION

JSMF14 KWNO     LAMP BUFR SOUTH CENTRAL REGION

JSMF15 KWNO     LAMP BUFR ROCKY MOUNTAINS REGION

JSMF16 KWNO     LAMP BUFR WEST COAST REGION

JSMF17 KWNO     LAMP BUFR ALASKA

 

Table 2: Communication Identifiers for the GFS-Based LAMP

Products in ASCII format

 

Listed below are the WMO headings and AWIPS identifier. This

heading has not changed.

 

WMO HEADING     AWIPS ID

-----------     --------

FOUS11 KWNO     LAVUSA

 

Table 3a: Communication Identifiers for the upgraded 5-km GFS-

Based LAMP Products Lightning products in GRIB2 format

 

Each GRIB2 product has a unique WMO header.  Listed below are

representations of the WMO headings.  These headings have not

changed.

 

WMO HEADING     ELEMENT

-----------     -------

LAUXXX KWNO     2-HR PROBABILITY OF LIGHTNING AT 5-KM

LBUXXX KWNO     2-HR CATEGORICAL FORECASTS OF LIGHTNING

                 OCCURRING at 5-KM

 

Table 3b: Communication Identifiers for the new 2.5-km GFS-Based

LAMP Products Lightning and Convection products in

GRIB2 format

 

Each GRIB2 product has a unique WMO header. Listed below are

representations of the WMO headings. These headings are new.

 

WMO HEADING     ELEMENT

-----------     -------

LCUXXX KWNO     2-HR PROBABILITY OF LIGHTNING AT 2.5-KM

LDUXXX KWNO     2-HR CATEGORICAL FORECAST POTENTIAL OF

                LIGHTNING OCCURRING at 2.5-KM

LEUXXX KWNO     2-HR PROBABILITY OF CONVECTION AT 2.5-KM

LFUXXX KWNO     2-HR CATEGORICAL FORECAST POTENTIAL OF

                CONVECTION OCCURRING at 2.5-KM

 

If you have technical comments or questions, please contact:

 

Judy Ghirardelli

National Weather Service

Meteorological Development Laboratory

Judy.Ghirardelli@noaa.gov

301-713-0056 x194

 

Links to the LAMP products and descriptions can found at:

 

   http://www.nws.noaa.gov/mdl/gfslamp/gfslamp.shtml

 

National Public Information Statements are online at:

 

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

 

$$