NOUS41 KWBC 111449
PNSWSH

SERVICE CHANGE NOTICE 08-46
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1050 AM EDT FRI JUL 11 2008

TO:      NATIONAL WEATHER SERVICE /NWS/ OFFICES
         FEDERAL AVIATION ADMINISTRATION /FAA/ USERS
         FAMILY OF SERVICES /FOS/ SUBSCRIBERS
         OTHER USERS OF NWS AVIATION FORECASTS

FROM:    KEVIN L. JOHNSTON
         CHIEF...AVIATION SERVICES BRANCH 
     
SUBJECT: REMINDER: FORMAT CHANGE FOR TERMINAL AERODROME FORECASTS
         /TAFS/ FROM 24-HOUR FORMAT TO 30-HOUR FORMAT: 
         EFFECTIVE NOVEMBER 5 2008

REFER TO:  SCN 08-15...TIN 08-16... TIN 08-17... TIN 08-18... TIN 
08-24... TIN 08-25...AND TIN 08-30. 

EFFECTIVE NOVEMBER 5 2008 ALL TAFS ISSUED BY NWS WILL CHANGE THE 
DATE AND TIME INDICATOR FORMAT IN THE TAF FROM THE PRESENT 24-HOUR 
FORMAT TO A NEW 30-HOUR FORMAT CONSISTENT WITH NEW INTERNATIONAL 
CIVIL AVIATION ORGANIZATION /ICAO/ RULES.  THIS FORMAT CHANGE IS 
PART OF AN INTERNATIONAL EFFORT TO IMPLEMENT A CONSISTENT TAF 
FORMAT EVEN AS TAF VALID TIMES RANGE FROM A FEW HOURS UP TO AND 
INCLUDING 30 HOURS.  ALL OF THE NEARLY 625 TAFS ISSUED BY NWS WILL 
BE AFFECTED BY THIS CHANGE.  A TABLE LISTING ALL THE AFFECTED TAFS 
IS LOCATED AT /USE LOWER CASE LETTERS/:

     HTTP://WWW.WEATHER.GOV/OS/AVIATION/PDFS/30_HR_TAF_TABLE1.PDF

FEDERAL AVIATION ADMINISTRATION /FAA/ PERSONNEL AND OTHER EXTERNAL 
USERS RECEIVING NWS TAFS IN THE TAF COLLECTIVES BELOW WILL ALSO 
NEED TO TAKE ACTION TO ENSURE CONTINUED ABILITY TO DECODE TAFS. 

   WMO HEADINGS     AVAILABLE TO THE FOLLOWING CUSTOMERS
   
   FTUS80 KWBC      NON-FAA DOMESTIC AND FAMILY OF SERVICES

   FTUS90 KWBC      FAA WEATHER MESSAGE SWITCHING CENTER 
                    AND FAA FACILITIES

   FTUS52 KWBC      GLOBAL TELECOMMUNICATION SYSTEM CUSTOMERS

NWS WILL SEND A MONTHLY TEST TAFS SO USERS CAN CHECK AND EVALUATE 
THEIR ABILITY TO DECODE THE NEW DATE AND TIME FORMAT. A SEPARATE 
TECHNICAL INFORMATION NOTICE WILL DETAIL THE TEST STRUCTURE AND 
METHOD. IN ADDITION REMINDERS OF THE TEST TAF WILL BE PROVIDED 
THREE DAYS BEFORE THE SCHEDULED TEST DAY. A TAF TESTBED CAN BE 
FOUND AT /USE LOWER CASE LETTERS/:

     HTTP://WWW.WEATHER.GOV/OS/AVIATION/TAF_TESTBED.HTM

IN ADDITION...TAFS FOR 32 LARGE AIRPORTS WILL BECOME VALID FOR 30 
HOURS.  THE SPECIFIC AIRPORTS AND TAFS SCHEDULED TO HAVE EXTENDED 
VALID TIMES WERE ANNOUNCED IN SEPARATE NOTICES...SEE TIN 08-16... 
TIN 08-17... TIN 08-18... TIN 08-24... TIN 08-25...AND TIN 08-30.   

NATIONAL GUIDELINES REGARDING THE TAF WILL BE INCLUDED IN AN 
APPENDIX AS PART OF A FUTURE UPDATE OF NWS INSTRUCTION /NWSI/ 10-
813 TERMINAL AERODROME FORECASTS AT /USE LOWER CASE LETTERS/:

    HTTP://WWW.NWS.NOAA.GOV/DIRECTIVES/SYM/PD01008013CURR.PDF

GUIDANCE TO NWS FORECASTERS FOR EDITING THE NEW TAF FORMAT WILL BE 
PROVIDED AT /USE LOWER CASE LETTERS/:

    HTTP://AVIATIONWEATHER.GOV/NOTICE/TAF30.PHP

THIS SERVICE CHANGE NOTICE WILL BE REPEATED IN SEPTEMBER 2008 TO 
REMIND USERS THAT TAF FORMATS WILL CHANGE NOVEMBER 5 2008.

REPEATING: THIS CHANGE IS EFFECTIVE NOVEMBER 5 2008...AND WILL 
AFFECT ALL TAFS PRODUCED BY NWS.  

FOR QUESTIONS REGARDING THIS SERVICE CHANGE NOTICE PLEASE CONTACT:

    BETH MCNULTY
    NATIONAL WEATHER SERVICE
    AVIATION SERVICES BRANCH
    1325 EAST WEST HIGHWAY
    SILVER SPRING MD 20910
    PHONE: 301-713-1726 EXT 116
    EMAIL: BETH.MCNULTY@NOAA.GOV

NWS SERVICE CHANGE NOTICES ARE ONLINE AT /USE LOWER CASE/:

    HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM

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