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Note: CORRECTION
WSHPNSNMC
NOUS41 KWBC 242223 COR
NATIONAL TECHNICAL INFORMATION MESSAGE /NTIM/ 96-16...CORRECTION
NATIONAL WEATHER SERVICE HEADQUARTERS
625 PM EDT MON JUN 24 1996
TO: USERS OF NWS-PREPARED AVIATION TERMINAL FORECASTS
FROM: THERESE Z. PIERCE
CHIEF - INTEGRATED HYDROMETEOROLOGICAL SERVICES CORE
SUBJECT: METAR/TAF IMPLEMENTATION: WHAT HAPPENS TO TERMINAL
FORECASTS AND TWEBS EFFECTIVE JULY 1 1996 BETWEEN
0700 AND 0800 UTC
EFFECTIVE 0800Z JULY 1 1996 THE UNITED STATES WILL IMPLEMENT THE
METAR AND TAF CODES. ALL HOURLY SURFACE OBSERVATIONS IN THE
DOMESTIC CODE (SAOS) AND TERMINAL FORECASTS IN THE DOMESTIC CODE
(FTAS) WILL BE DISCONTINUED AFTER 0800 UTC ON JULY 1 1996.
INCLUDED BELOW ARE THE SPECIFIC INSTRUCTIONS FOR NWS FIELD
OFFICES AS TO WHAT EXACTLY TO DO WITH THE TERMINAL FORECASTS
(TAFS AND FTAS) AND THE TRANSCRIBED WEATHER ENROUTE BROADCASTS
(TWEBS) BETWEEN 0700 UTC AND 0800 UTC ON JULY 1 1996.
TAF: TAFS (TERMINAL FORECASTS IN THE INTERNATIONAL CODE) ARE
ISSUED 4 TIMES PER DAY...VALID FOR 24-HOURS BASED ON UTC TIMES
(SEE BELOW). BEGINNING ON JULY 1 1996...TAFS WILL BE ISSUED 20-
40 MINUTES BEFORE THE BEGINNING OF THE VALID TIME AS FOLLOWS:
TAF ISSUANCE TIME (UTC) TAF VALID TIME (UTC)
2320-2340 0000
0520-0540 0600
1120-1340 1200
1720-2340 1800
THE METAR/TAF IMPLEMENTATION WILL TAKE PLACE AT 0800 UTC ON
JULY 1 1996...A PERIOD OF LOW AIR TRAFFIC. 0800 UTC IS NOT A
SCHEDULED TAF ISSUANCE TIME. ON JULY 1 1996...A SPECIAL TAF
VALID AT 0800 UTC SHALL BE ISSUED BY ALL NWS OFFICES WITH
TERMINAL FORECAST RESPONSIBILITY...INCLUDING THOSE OFFICES WHO
CURRENTLY PREPARE TAFS (BEFORE 7/1/96). THE SPECIAL 0800 UTC TAF
SHALL BE ISSUED BETWEEN 0720 AND 0740 UTC AND WILL BE VALID FROM
0800 JULY 1 1996 UNTIL 0600 UTC JULY 2 1996...AS SHOWN BELOW:
TAF
TTAA00 KBOS 010700 ***CORRECTED TIME IN WMO HEADER***
KBDL 010724Z 010806 WIND VIS WX CLOUDS (WIND SHEAR)...
FTAS ARE ISSUED 3 TIMES PER DAY BASED ON LOCAL TIME (BY TIME
ZONE). THE LAST FTAS SHALL BE ISSUED AS FOLLOWS:
TIME ZONE LAST FTA ISSUANCE TIME (UTC)
ATLANTIC 0435 UTC JULY 1 1996
EASTERN 2345 UTC JUNE 30 1996
CENTRAL 2345 UTC JUNE 30 1996
MOUNTAIN 0045 UTC JULY 1 1996
PACIFIC 0145 UTC JULY 1 1996
ALASKA 0345 UTC JULY 1 1996
HAWAII/ALEUTIAN 0545 UTC JULY 1 1996
THE LAST FTA...ISSUED AS SHOWN ABOVE... SHALL INCLUDE THE
FOLLOWING REMARK AT THE END OF THE FORECAST:
LAST FT - NO AMD AFT 0800 UTC
BETWEEN THE ISSUANCE OF THE SPECIAL 0800 UTC TAF (0720-0740 UTC)
AND THE BEGINNING OF THE SPECIAL TAF'S VALID PERIOD (0800 UTC)
BOTH THE LAST FTA AND THE SPECIAL 0800 UTC TAF NEED TO BE
MONITORED AND AMENDED AS NECESSARY. AFTER 0800 UTC...ALL FTAS
BECOME INACTIVE AND NEED NOT BE MONITORED NOR AMENDED.
TWEBS: AS PART OF THE OVERALL METAR/TAF IMPLEMENTATION...THE
FREQUENCY AND ISSUANCE SCHEDULE FOR TWEBS WILL CHANGE ON
JULY 1 1996. TWEBS ARE CURRENTLY ISSUED 3 TIMES PER DAY
FOLLOWING THE FTAS...BASED ON LOCAL TIME. BEGINNING ON
JULY 1 1996...TWEBS SHALL BE ISSUED 4 TIMES PER DAY...BASED ON
UTC TIME...2 HOURS AFTER THE SCHEDULED TAFS...AS FOLLOWS:
TWEB ISSUANCE TIME (UTC) TWEB VALID TIME (UTC)
0130-0140 0200
0730-0740 0800
1330-1340 1400
2130-2340 2000
ON JULY 1 1996...THE FIRST TWEB USING THE NEW SCHEDULE AND CODING
CONVENTIONS SHALL BE ISSUED AT 1330 UTC JULY 1 1996. ON JULY 1
1996 ONLY...THE 0800Z TWEB ISSUANCE WILL BE SKIPPED IN ORDER TO
GIVE FORECASTERS TIME TO SOLVE ANY PROBLEMS THAT MAY ARISE WITH
THE METAR/TAF CHANGEOVER.
IF THE TWEB ISSUANCE PRIOR TO 0800 UTC NEEDS TO BE AMENDED BEFORE
0800 UTC JULY 1...THE AMENDMENT SHALL USE THE CURRENT SAO/FTA
CODING. IF A TWEB AMENDMENT IS REQUIRED AT 0800 UTC OR LATER THE
AMENDMENT SHALL USE THE METAR/TAF CODING. THE TWEB ISSUED ON
JULY 1 1996 AT 1400 UTC AND ALL SUBSEQUENT ISSUANCES SHALL USE
THE METAR/TAF CODING AND 4 TIMES PER DAY ISSUANCE SCHEDULE.
REFER TO WEATHER SERVICE OPERATIONS MANUAL D-31...AVIATION
TERMINAL FORECASTS (DRAFT DATED 6/20/96) AND D-30... TRANSCRIBED
WEATHER BROADCAST TEXT PRODUCTS (DRAFT DATED 6/20/96) FOR MORE
DETAILS ON TAFS AND TWEBS. THESE DOCUMENTS ARE AVAILABLE ON THE
NWS' METAR/TAF HOME PAGE AT THE FOLLOWING ADDRESS ON THE WORLD
WIDE WEB:
HTTP://WWW.NWS.NOAA.GOV/OSO/OSO1/OSO12/METAR.HTM
IF YOU HAVE QUESTIONS...PLEASE CONTACT:
TAFS: TWEBS:
CHRIS ALEX JIM ROETS
(301)-713-1726 X 142 (301)-713-1726 X 144
CALEX@xxxxxxxxxxxxxxxxxxxxxx JROETS@xxxxxxxxxxxxxxxxxxxxxx
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