960624: METAR/TAF Implementation-NOUS (fwd)

256 
NOUS41 KWBC 242032
PNSNMC
 
NATIONAL TECHNICAL INFORMATION MESSAGE /NTIM/ 96-16
NATIONAL WEATHER SERVICE HEADQUARTERS
430 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 01700
     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
END