NOUS41 KWBC 171330
PNSWSH

SERVICE CHANGE NOTICE 08-55
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
930 AM EDT WED SEP 17 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 0000 UTC NOVEMBER 5 2008

REFER TO:  SCN 08-15... SCN 08-46... TIN 08-16... TIN 08-17... TIN 
08-18... TIN 08-24... TIN 08-25... TIN 08-30...AND TIN 08-73 

EFFECTIVE AT 0000 COORDINATED UNIVERSAL TIME /UTC/ 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. THE EFFECTIVE TIME OF 0000 UTC WAS SET 
BY ICAO AND COORDINATED THROUGHOUT ITS MEMBERSHIP.  

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/:

  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

TEST TAFS WILL BE PROVIDED FOR USERS TO CHECK AND EVALUATE THEIR 
ABILITY TO DECODE THE NEW DATE AND TIME FORMAT. THESE TESTS WILL 
BE OCCURRING AT LEAST ONCE A WEEK THROUGH SEPTEMBER AND OCTOBER.  
TIN 08-73 DETAILS THE TEST STRUCTURE AND METHOD.  A TAF TESTBED 
CAN BE FOUND AT /USE LOWER CASE/:

  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 TINS 
08-16... 08-17... 08-18... 08-24... 08-25...AND 08-30.  THESE 
CHANGES WILL TAKE EFFECT AT 0000 UTC.   

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

  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

REPEATING: THIS CHANGE IS EFFECTIVE AT 0000 UTC 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
  301-713-1726 EXT 116
  BETH.MCNULTY@NOAA.GOV

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

  HTTP://WWW.WEATHER.GOV/OS/NOTIF.HTM

$$
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