NOUS41 KWBC 091850
PNSWSH 

TECHNICAL IMPLEMENTATION NOTICE 04-09...RESENT
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
155 PM EST TUE MAR 9 2004

TO:       FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER 
          WIRE SERVICE /NWWS/ SUBSCRIBERS...EMERGENCY MANAGERS 
          WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS... 
          NOAAPORT SUBSCRIBERS...OTHER NATIONAL WEATHER SERVICE
          /NWS/ CUSTOMERS AND PARTNERS...NWS EMPLOYEES 

FROM:     PAUL HIRSCHBERG
          CHIEF...SCIENCE PLANS BRANCH
          OFFICE OF SCIENCE AND TECHNOLOGY /OST/ 

SUBJECT:  CHANGES IN GLOBAL FORECAST SYSTEM /GFS/ MODEL OUTPUT
          STATISTICS /MOS/ GUIDANCE FOR TOTAL SKY COVER...
          CEILING HEIGHT...AND VISIBILITY...EFFECTIVE MAY 18 2004

RESENT DUE TO POSSIBLE GARBLING OF ORIGINAL MESSAGE...WHICH WAS 
TRANSMITTED MARCH 4 2004

NOTE...THE FOLLOWING CHANGES HAVE NO IMPACT ON NOAA WEATHER 
WIRE SUBSCRIBERS 

ATTENTION USERS OF THE MODEL OUTPUT STATISTICS /MOS/ GUIDANCE:

ON TUESDAY...MAY 18 2004...WITH THE 1200 COORDINATED UNIVERSAL
TIME /UTC/ MODEL CYCLE...THE NWS WILL CHANGE THE CONTENT OF THE
GLOBAL FORECAST SYSTEM /GFS/ MODEL OUTPUT STATISTICS /MOS/
GUIDANCE.   THE DEFINITION OF CATEGORIES OF TOTAL SKY COVER AND
CEILING HEIGHT WILL BE MODIFIED TO DISTINGUISH BETWEEN FEW /FW/
AND SCATTERED /SC/ CLOUDS AND BETWEEN CEILINGS OF 1000-1900 FT
AND 2000-3000 FT.  DEFINITIONS OF THE CATEGORICAL VISIBILITY
GUIDANCE WILL ALSO BE MODIFIED.

THE NEW SKY COVER CATEGORIES WILL BE AS FOLLOWS:

     CL = CLEAR
     FW = > 0 to 2 OCTAS OF TOTAL SKY COVER
     SC = > 2 to 4 OCTAS OF TOTAL SKY COVER
     BK = > 4 to < 8 OCTAS OF TOTAL SKY COVER
     OV = 8 OCTAS OF TOTAL SKY COVER OR TOTALLY OBSCURED

THE NEW CATEGORICAL NUMBERS FOR CEILING HEIGHT WILL BE AS
FOLLOWS: 

     1 = < 200 FT
     2 = 200 TO 400 FT
     3 = 500 TO 900 FT
     4 = 1000 TO 1900 FT
     5 = 2000 TO 3000 FT
     6 = 3100 TO 6500 FT
     7 = 6600 TO 12000 FT
     8 = > 12000 FT OR UNLIMITED. 

DEFINITIONS OF THE CATEGORICAL VISIBILITY GUIDANCE WILL BE
CHANGED TO THE FOLLOWING: 

     1 = < 1/2 MI
     2 = 1/2 MI TO < 1 MI
     3 = 1 TO < 2 MI
     4 = 2 TO < 3 MI
     5 = 3 TO 5 MI
     6 = 6 MI
     7 = > 6 MI

TABLE 1.  COMMUNICATION IDENTIFIERS FOR THE GFS-BASED MOS TEXT
PRODUCTS WHICH WILL BE MODIFIED.  THE AWIPS IDS ARE
MAVXXX...WHERE THE FINAL XXX DENOTES THE GEOGRAPHIC REGION FOR
WHICH THE GUIDANCE IS VALID.

     WMO HEADING    AWIPS ID       GEOGRAPHIC REGION

     FOPA20 KWNO    MAVPA0         PACIFIC ISLANDS
     FOUS21 KWNO    MAVNE1         NORTHEAST CONUS
     FOUS22 KWNO    MAVSE1         SOUTHEAST CONUS
     FOUS23 KWNO    MAVNC1         NORTH CENTRAL CONUS
     FOUS24 KWNO    MAVSC1         SOUTH CENTRAL CONUS
     FOUS25 KWNO    MAVRM1         ROCKY MOUNTAIN CONUS
     FOUS26 KWNO    MAVWC0         WEST COAST CONUS
     FOAK37 KWNO    MAVAJK         SOUTHEAST ALASKA /JUNEAU/
     FOAK38 KWNO    MAVAFC         CENTRAL ALASKA  /ANCHORAGE /
     FOAK39 KWNO    MAVAFG         NORTHERN ALASKA /FAIRBANKS/
                           
A TECHNICAL DESCRIPTION OF THE MODIFIED SHORT-RANGE GFS MOS
FORMAT CAN BE FOUND AT THE URL LISTED BELOW /USE LOWER CASE
LETTERS/:

    http://www.nws.noaa.gov/mdl/synop/tpb/gfsmsg2004t0012.pdf

    http://www.nws.noaa.gov/mdl/synop/tpb/gfsmsg2004t0618.pdf

LINKS TO THESE PRODUCTS...ALONG WITH DESCRIPTIONS...CAN BE FOUND
AT /USE LOWER CASE LETTERS/:

        http://www.nws.noaa.gov/mdl/synop/products.shtml

NO CHANGES WILL BE MADE TO THE BUFR /GRIDDED BINARY/ MOS MESSAGES
AT THIS TIME.

IF YOU HAVE ANY QUESTIONS ABOUT THESE CHANGES TO THE MOS GUIDANCE
SYSTEM...PLEASE CONTACT:

       PAUL DALLAVALLE 
       MDL/SILVER SPRING MARYLAND 
       PHONE:   301-713-0023 EXT. 135 
       E-MAIL:  PAUL.DALLAVALLE@NOAA.GOV 

THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE
ONLINE AT /USE LOWER CASE LETTERS/:

        http://www.nws.noaa.gov/os/notif.htm

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