NOUS41 KWBC 241739

PNSWSH      

 

Technical Implementation Notice 13-50

National Weather Service Headquarters Washington DC

138 PM EST Tue Dec 24 2013

 

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: Changes to the Localized Aviation Model Output

         Statistics Program (LAMP) Products and addition

         Of Convection Guidance and upgrade to

         Lightning Guidance: Comment period extended

         to January 16, 2014, and effective date to be

         March 11, 2014

 

Effective on or about Tuesday, March 11, 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 will make a final decision on implementation these

proposed products in early March 2014. If approved, this

guidance will be implemented on Tuesday, March 11, 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

 

$$