913
NOUS41 KWBC 101450 AAA
PNSWSH
SERVICE CHANGE NOTICE 25-62 UPDATED
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING MD
1050 AM EDT THU OCT 9 2025
TO: SUBSCRIBERS
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS, USERS AND EMPLOYEES
FROM: GEOFF MANIKIN
NWS OFFICE OF SCIENCE AND TECHNOLOGY INTEGRATION
METEOROLOGICAL DEVELOPMENT LABORATORY
SUBJECT: UPDATED: CHANGES AND ADDITIONS TO LAMP STATION-BASED
AND GRIDDED GUIDANCE EFFECTIVE OCTOBER 9, 2025.
UPDATED TO REVERT THE CHANGE TO THE STATION VISIBILITY
THRESHOLDS THAT WAS IMPLEMENTED WITH THE LAMP/GLMP V2.7 UPGRADE
ON SEPTEMBER 16, 2025 (SEE CHANGE #2 IN THE ORIGINAL NOTICE
BELOW), AND TO CORRECT A BUG WITH MISSING LAMP WIND GUST
GUIDANCE AT THREE METAR SITES.THIS UPDATE WILL TAKE EFFECT
BEGINNING WITH THE 1500 UTC CYCLE ON OCTOBER 9, 2025.
THE STATION THRESHOLD CHANGE RESULTED IN INCONSISTENCIES IN THE
GLMP VISIBILITY GUIDANCE AT GRID POINTS THAT ARE COINCIDENT WITH
A LAMP STATION AND IS ADVERSELY IMPACTING THE NATIONAL BLEND OF
MODELS (NBM). RESTORING THE ORIGINAL STATION THRESHOLDS WILL
CORRECT THE INCONSISTENCIES IN NBM VISIBILITY. THE NEW LAMP
STATION VISIBILITY THRESHOLDS WILL INSTEAD BE IMPLEMENTED IN A
FUTURE LAMP/GLMP UPGRADE. ADDITIONALLY, LAMP WIND GUST GUIDANCE
THAT WAS INADVERTENTLY REMOVED WITH THE V2.7 UPGRADE WILL BE
RESTORED FOR THE FOLLOWING STATIONS: 1) KJPX - EAST HAMPTON, NY,
2) KBCR - TRI-COUNTY AIRPORT, FL, AND 3) KGDA - MARION, KY.
THE ORIGINAL NOTICE FOLLOWS.
ON OR ABOUT SEPTEMBER 16, 2025, BEGINNING WITH THE 1400
COORDINATED UNIVERSAL TIME (UTC) MODEL RUN, THE NWS
METEOROLOGICAL DEVELOPMENT LABORATORY (MDL) WILL IMPLEMENT
CHANGES TO THE LOCALIZED AVIATION MODEL OUTPUT STATISTICS
PROGRAM (LAMP) STATION-BASED AND GRIDDED LAMP (GLMP) GUIDANCE.
COMMENTS/FEEDBACK ON THIS UPGRADE WERE PREVIOUSLY SOLICITED
PUBLICLY FROM MAY 1-30, 2025 VIA THIS PUBLIC INFORMATION
STATEMENT:
HTTPS://WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF_2025/PNS25-
28_LAMP_GLMP_V2.7.PDF
IN THE EVENT THAT THE IMPLEMENTATION DATE IS DECLARED A CRITICAL
WEATHER DAY (CWD), AN ENHANCED CAUTION EVENT (ECE), OR OTHER
SIGNIFICANT WEATHER IS OCCURRING OR IS ANTICIPATED TO OCCUR,
IMPLEMENTATION OF THIS CHANGE WILL TAKE PLACE AT 1630 UTC ON THE
NEXT WEEKDAY NOT DECLARED A CWD AND WHEN NO SIGNIFICANT WEATHER
IS OCCURRING.
LAMP/GLMP V2.7 WILL INCLUDE THE FOLLOWING ENHANCEMENTS/CHANGES
IN SUPPORT OF THE NATIONAL BLEND OF MODELS (NBM) AND OTHER NWS
INITIATIVES:
1) ADDITION OF STATION-BASED GUIDANCE FOR CEILING HEIGHT AND
VISIBILITY THAT PROVIDES THE FORECASTED START AND END (AKA ONSET
AND CESSATION) TIMES OF AVIATION FLIGHT CATEGORIES AND PROVIDES
PROBABILISTIC INFORMATION. THE GUIDANCE WILL BE MADE AVAILABLE
ON NCEP WEB SERVICES (NOMADS) IN THREE TEXT BULLETIN FORMATS:
A. AN EXPANDED SUB-HOURLY BULLETIN CONTAINING GUIDANCE VALID FOR
15-MINUTE PERIODS OUT TO SIX HOURS, UPDATING EVERY 15 MINUTES
(96 CYCLES PER DAY), FOR 1818 CONUS STATIONS. THE EXPANDED SUB-
HOURLY BULLETINS WILL CONTAIN GUIDANCE FOR:
I. THE LOWEST FORECASTED COMBINED FLIGHT CATEGORY DURING THE 15-
MINUTE PERIOD.
II. THE FORECASTED START, PREVAILING, AND END TIMES OF EACH
COMBINED FLIGHT CATEGORY.
III. THE LOWEST FORECASTED LAMP CATEGORICAL CEILING AND
CATEGORICAL VISIBILITY DURING THE 15-MINUTE PERIOD.
IV. CUMULATIVE PROBABILITIES FOR SPECIFIC CEILING CATEGORIES
OCCURRING DURING THE 15-MINUTE PERIOD.
V. CUMULATIVE PROBABILITIES FOR SPECIFIC VISIBILITY CATEGORIES
OCCURRING DURING THE 15-MINUTE PERIOD.
THE NEW SUB-HOURLY FILE WILL HAVE THE FOLLOWING NAMING FORMAT
"LMP.THHMMZ.FLTCAT.F0015-F0600.TXT" (WHERE HH IS THE LAMP CYCLE
HOUR AND MM IS THE LAMP CYCLE MINUTE).
THE PREVIOUS SUB-HOURLY BULLETIN THAT CONTAINS JUST THE LAMP
CATEGORIES, NAMED "LMP.THHMMZ.SUBHBULL.F0015-F0600.TXT" WILL NO
LONGER BE PRODUCED STARTING ON THE CHANGE DATE. ALSO, THE
PREVIOUSLY ADVERTISED “CIGH” LINE IN THE BULLETIN THAT INDICATED
THE LOWEST CEILING HEIGHT IN HUNDREDS OF FEET HAS BEEN REMOVED
FROM THE PRODUCT. INCLUDING THIS INFORMATION WOULD HAVE
RESULTED IN AN UNACCEPTABLE PRODUCTION DELAY DUE TO A DEPENDENCE
ON THE GLMP CEILING GRIDS.
B. A NEW EXTENDED FLIGHT CATEGORY BULLETIN CONTAINING GUIDANCE
FOR HOURLY PROJECTIONS OUT TO 38 HOURS, UPDATING EACH HOUR AT
THE NOMINAL HH:30 UTC LAMP CYCLE TIMES, FOR 1818 STATIONS. THE
EXTENDED BULLETINS WILL CONTAIN GUIDANCE FOR:
I. THE FORECASTED COMBINED FLIGHT CATEGORY AT THE HOUR.
II. THE FORECASTED START, PREVAILING, AND END TIMES OF EACH
COMBINED FLIGHT CATEGORY.
III. THE FORECASTED LAMP CATEGORICAL CEILING AND CATEGORICAL
VISIBILITY VALID AT THE HOUR.
IV. CUMULATIVE PROBABILITIES FOR SPECIFIC CEILING CATEGORIES
OCCURRING AT THE TOP OF THE HOUR.
V. CUMULATIVE PROBABILITIES FOR SPECIFIC VISIBILITY CATEGORIES
OCCURRING AT THE TOP OF THE HOUR.
THIS NEW FILE WILL HAVE THE FOLLOWING NAMING FORMAT
"LMP.THH30Z.FLTCAT.F001-F038.TXT" (WHERE HH IS THE LAMP CYCLE
HOUR).
C. A NEW SIMPLIFIED BULLETIN THAT INDICATES THE START DAY AND
TIME AND END DAY AND TIME IN UTC FOR EACH FLIGHT CATEGORY,
PRODUCED EVERY 15 MINUTES (96 CYCLES PER DAY) COVERING THE FIRST
SIX HOURS, AND PRODUCED HOURLY (24 CYCLES PER DAY) COVERING
FORECAST PROJECTIONS OUT TO 38 HOURS.
THE SIMPLIFIED BULLETINS WILL HAVE THE FOLLOWING NAMING FORMAT
"LMP.THHMMZ.SIMPBULL.F0015-F0600.TXT"
"LMP.THH30Z.SIMPBULL.F001-F038.TXT" (WHERE HH IS THE LAMP CYCLE
HOUR AND MM IS THE LAMP CYCLE MINUTE)
THE NEW AND MODIFIED TEXT BULLETIN PRODUCTS DESCRIBED ABOVE WILL
BE MADE AVAILABLE ON NCEP WEB SERVICES (NOMADS) BEGINNING ON THE
IMPLEMENTATION DATE (LOCATION AND FILE NAME DETAILS PROVIDED
BELOW). THESE PRODUCTS WILL NOT BE DISSEMINATED OVER THE
SATELLITE BROADCAST NETWORK (SBN) AT THIS TIME.
2) UPDATED HOURLY CATEGORICAL VISIBILITY GUIDANCE AT STATIONS TO
IMPROVE OVER-FORECAST BIASES. PRESENTLY, NATIONAL THRESHOLDS
WHICH DO NOT VARY BY STATION ARE USED FOR EACH LAMP VISIBILITY
CATEGORY. THIS HAS LED TO OVER-FORECASTING OF THE LOWER
VISIBILITY CATEGORIES IN SOME PARTS OF THE COUNTRY, PARTICULARLY
OVER THE EASTERN U.S. OFF THE COASTAL PLAIN. TO ADDRESS THIS
ISSUE, STATIONS WERE GROUPED BASED ON DECILES OF FORECAST BIAS
FOR EACH VISIBILITY CATEGORY, AND THEN THRESHOLDS WERE RE-
DERIVED FOR EACH DECILE GROUP THAT APPLY TO ALL STATIONS IN THE
GROUP. VERIFICATION SCORES FOR VISIBILITY ARE EITHER UNCHANGED
OR MODESTLY IMPROVED AT A MAJORITY OF LAMP STATIONS USING THE
REDEVELOPED THRESHOLDS. UPON IMPLEMENTATION, THE UPDATED
CATEGORICAL VISIBILITY GUIDANCE WILL BE REFLECTED IN THE HOURLY
LAMP “LAV” AND “LEV” TEXT BULLETINS AND BUFR MESSAGE.
3) ADDITION OF CEILING HEIGHT AND VISIBILITY GUIDANCE FOR 335
STATIONS IN THE “LAV” AND “LEV” TEXT BULLETINS AND BUFR
MESSAGE.
THESE STATIONS WERE ORIGINALLY ADDED TO THE LAMP SYSTEM IN 2023
FOR TEMPERATURE, DEWPOINT, AND WIND ELEMENTS. AVAILABILITY OF
LAMP GUIDANCE FOR THESE STATIONS IS NOW BEING EXPANDED TO
INCLUDE CATEGORICAL CEILING AND VISIBILITY. A LIST OF THE 335
STATIONS WITH ADDED CEILING AND VISIBILITY GUIDANCE CAN BE
VIEWED HERE HTTPS://VLAB.NOAA.GOV/WEB/MDL/LAMP-STNS-ADD-2023.
NOTE THAT THESE STATIONS WILL BE ADDED TO THE GLMP CEILING AND
VISIBILITY ANALYSES IN A FUTURE UPGRADE.
4) A BUG FIX TO CORRECT A MISREPRESENTATION OF UNLIMITED CEILING
HEIGHT IN THE ALASKA GLMP CEILING GRIDS. PRESENTLY, THE GLMP
DETERMINISTIC CEILING GRIDS FOR ALASKA CAN CONTAIN VALUES
GREATER THAN 12,000 FEET, WHICH IS UNINTENDED. THIS HAS BEEN
CORRECTED TO SET CEILINGS GREATER THAN 12,000 FEET TO A VALUE OF
“-100” IN THE DISSEMINATED GRIB2 OUTPUT.
MORE DETAILS ABOUT LAMP/GLMP PRODUCTS AND THIS IMPLEMENTATION
CAN BE FOUND ONLINE AT THE LAMP DOCUMENTATION WEB SITE:
HTTPS://VLAB.NOAA.GOV/WEB/MDL/LAMP-DOCUMENTATION
CHANGES TO DISSEMINATION:
ON THE CHANGE DATE, SOME LAMP AND GLMP FILES THAT PRESENTLY
RESIDE ON NOMADS WILL HAVE A NAME CHANGE. A LIST OF IMPACTED
FILES WITH THE OLD AND NEW FILE NAMES IS AVAILABLE AT THE
FOLLOWING LINK:
HTTPS://VLAB.NOAA.GOV/WEB/MDL/NOMADS-V2.7-FILENAME-CHANGES
THERE ARE NO CHANGES TO LAMP OR GLMP WMO HEADERS OR SBN ROUTING
WITH THIS IMPLEMENTATION. COMPLETE LISTS OF LAMP AND GLMP WMO
HEADERS (UNCHANGED FROM V2.6) CAN BE FOUND HERE:
HTTPS://VLAB.NOAA.GOV/DOCUMENTS/6609493/7858387/LAMPHEADERS_2024
_V2.6.DOCX.PDF
HTTPS://VLAB.NOAA.GOV/DOCUMENTS/6609493/7858387/GLMPHEADERS_2024
_V2.6.DOCX.PDF
CURRENT MODEL DATA IS AVAILABLE HERE:
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/LMP/PROD
FTP://FTP.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/LMP/PROD
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GLMP/PROD
FTP://FTP.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GLMP/PROD
A CONSISTENT PARALLEL FEED OF DATA WILL BE AVAILABLE ON THE NCEP
PARALLEL NOMADS SITE BEGINNING AT LEAST 30 DAYS PRIOR TO
IMPLEMENTATION AT THE FOLLOWING LOCATIONS:
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/LMP/PARA
FTP://FTP.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/LMP/PARA
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GLMP/PARA
FTP://FTP.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GLMP/PARA
QUESTIONS CONCERNING PARALLEL DATA SHOULD BE DIRECTED TO THE
NCEP HPC DATAFLOW TEAM AT NCEP.PMB.DATAFLOW@NOAA.GOV.
NCEP ENCOURAGES USERS TO ENSURE THEIR DECODERS ARE FLEXIBLE AND
ARE ABLE TO ADEQUATELY HANDLE CHANGES IN CONTENT FORMAT
(INCLUDING FORMAT AND ORDER OF VARIABLES) AND ANY VOLUME CHANGES
THAT MAY BE FORTHCOMING. THESE ELEMENTS MAY CHANGE WITH FUTURE
NCEP MODEL IMPLEMENTATIONS. NCEP WILL MAKE EVERY ATTEMPT TO
ALERT USERS TO THESE CHANGES PRIOR TO ANY IMPLEMENTATIONS.
QUESTIONS, COMMENTS OR REQUESTS REGARDING THIS CHANGE SHOULD BE
DIRECTED TO THE CONTACTS BELOW.
GEOFF MANIKIN
EMAIL: GEOFFREY.MANIKIN@NOAA.GOV
METEOROLOGICAL DEVELOPMENT LABORATORY
STATISTICAL MODELING DIVISION CHIEF
SILVER SPRING, MD
AND/OR
PHIL SHAFER
EMAIL: PHIL.SHAFER@NOAA.GOV
METEOROLOGICAL DEVELOPMENT LABORATORY
DECISION SUPPORT DIVISION
LAMP TEAM LEAD
SILVER SPRING, MD
FOR QUESTIONS RELATING TO DATAFLOW, PLEASE CONTACT:
MARGARET CURTIS
NCEP CENTRAL OPERATIONS HPC DATAFLOW TEAM LEAD
NCEP.PMB.DATAFLOW@NOAA.GOV
LINKS TO THE LAMP PRODUCTS AND DESCRIPTIONS CAN BE FOUND AT:
HTTPS://VLAB.NOAA.GOV/WEB/MDL/LAMP
NWS SERVICE CHANGE NOTICES ARE ONLINE AT:
HTTPS://WWW.WEATHER.GOV/NOTIFICATION/
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