NOUS41 KWBC 101228 AAB



Technical Implementation Notice 11-46 AAB

National Weather Service Headquarters Washington DC 

828 AM EDT Tue Jul 10 2012


To:       Subscribers:

          - Family of Services

          - NOAA Weather Wire Service

          - Emergency Managers Weather Information Network

          - NOAAPORT

          Other NWS partners, users and NWS employees


From:     Tim McClung

          Science Plans Branch Chief

          Office of Science and Technology


Subject:  Amended: Changes to Localized Aviation Model Output

          Statistics Program (LAMP) Products:  Effective

          July 17, 2012. 


Amended to set the implementation date for Tuesday, July 17,

2012. Users are cautioned that if a Critical Weather Day (CWD)

designation is in effect on July 17, this implementation will be

delayed until the conclusion of CWD.  You can monitor the CWD

status at the following webpage:


Effective on Tuesday, July 17, 2012, beginning with the 1600

Coordinated Universal Time (UTC) run, the NWS Meteorological

Development Laboratory (MDL) will update the Localized Aviation

Model Output Statistics Program (LAMP) system.


The LAMP changes include:


1. Replacing the current LAMP total sky cover guidance with

new opaque sky cover guidance, which is dependent on cloud



The LAMP sky cover guidance predicts an estimate of the total

percentage of the sky covered by clouds in terms of the five

categories reported in the METAR observations: clear, few,

scattered, broken, or overcast. The current LAMP total sky cover

guidance does not distinguish between opaque and translucent

cloud cover. 


The new LAMP sky cover will produce an estimate of opaque clouds.

The anticipated effect of this change will be to decrease the

number of broken or overcast forecasts and to increase the number

of clear or few forecasts when only cirrus clouds are expected. 

This change will make the LAMP guidance consistent with both the

NWS definition of sky cover, as well as the Global Forecast

System (GFS)-based MOS definition of sky cover. See TIN 07-34 for

details on GFS-based MOS opaque sky cover change.


The LAMP total sky cover currently available in the LAMP public

text bulletins (known by their AWIPS ids LAV) and labeled as CLD

will be replaced with the LAMP opaque sky cover. The CLD label

will not change. Likewise, the LAMP total sky cover currently

available in the BUFR message will be replaced with the LAMP

opaque sky cover. This change to the LAMP BUFR message will be

transparent to users with no changes to the descriptors in the

BUFR file. 


2. Redeveloped ceiling height and conditional ceiling height

equations to produce improved forecast guidance.


3. NWS will add 119 stations to the LAMP text bulletins and BUFR

products. These changes will be reflected in the new equations

for opaque sky cover, and the redeveloped ceiling height and

conditional ceiling height equations. These changes will also be

reflected in the guidance for the following elements:


Precipitation occurring on the hour

Precipitation in a 6-hour period

Precipitation in a 12-hour period

Thunderstorms in a 2-hour period

Precipitation type


Conditional visibility

Obstruction to vision


These changes will slightly alter the format of the LAV text

products because new lines will be added to the existing

bulletins to accommodate the new stations. In addition, some

stations might not have had guidance for all of the above

elements prior to this change, and with this change, guidance

will now be produced for those elements for those stations.


These changes will also alter the contents of the LAMP BUFR

messages because new guidance will be available. The

communication identifiers for the text and BUFR products are

shown in Tables 1 and 2 below.


Table 1: Communication identifiers for the GFS-based LAMP

products in ASCII format. Listed below are the WMO heading and

the AWIPS identifier.


WMO heading     AWIPS ID

-----------     --------



Table 2: Communication identifiers for the GFS-based LAMP

products in BUFR format.  Listed below are the WMO headings. 


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 Region


A Web page providing additional details of these changes,

including a link to the list of new stations, is online at:


If you have technical comments or questions, please contact:


Judy Ghirardelli

National Weather Service

Meteorological Development Laboratory

301-713-0056 x194


Links to the LAMP products and descriptions can found at:


National Public Information Statements are online at: