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NOUS41 KWBC 241541
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PUBLIC INFO. STATEMENT ... TECHNICAL INFORMATION NOTICE 01-20
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1145 AM EDT TUE JUL 24 2001
TO: FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER
WIRE SERVICE /NWWS/ SUBSCRIBERS...EMERGENCY MANAGERS
WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS...
OTHER NATIONAL WEATHER SERVICE /NWS/ CUSTOMERS AND
PARTNERS...NWS EMPLOYEES
FROM: PAUL NIPKO
ACTING CHAIR...NWS COMMITTEE ON ANALYSIS AND FORECAST
TECHNIQUES IMPLEMENTATION /CAFTI/
SUBJECT: CHANGES IMPLEMENTED IN THE AVIATION MODEL /AVN/
MODEL OUTPUT STATISTICS /MOS/ GUIDANCE...EFFECTIVE
JULY 24 2001 AT 1200 UTC
...THE FOLLOWING CHANGES HAVE NO IMPACT ON NOAA WEATHER WIRE
SERVICE OR EMWIN SUBSCRIBERS...
EFFECTIVE WITH THE 1200 UTC FORECAST CYCLE ON JULY 24 2001...
GUIDANCE FOR CATEGORICAL FORECASTS OF PRECIPITATION AMOUNT /QPF/
HAS BEEN ADDED TO THE NEW AVIATION MODEL /AVN/ MODEL OUTPUT
STATISTICS /MOS/ MESSAGES. THESE MESSAGES ARE IDENTIFIED WITH
THE FOLLOWING WORLD METEOROLOGICAL ORGANIZATION /WMO/ HEADERS:
FOPA20 KWNO
FOUS21 KWNO-FOUS26 KWNO
FOAK37 KWNO-FOAK39 KWNO
AND ARE STORED AS MAV PRODUCTS IN THE AWIPS TEXT DATA BASE.
IN ADDITION...NEW FORECAST EQUATIONS TO PREDICT THE PROBABILITY
OF PRECIPITATION /POP/ WERE IMPLEMENTED. THE POP GUIDANCE
PROVIDES FORECASTS OF THE PROBABILITY OF PRECIPITATION EQUALING
OR EXCEEDING 0.01 INCHES OF LIQUID-EQUIVALENT AMOUNT IN A 6- OR
12-H PERIOD. THE 6-H PROBABILITIES FOR ALL SITES ARE LABELED AS
P06 AND ARE VALID 6-12...12-18...18-24... OUT TO 66-72 HOURS
AFTER 0000 OR 1200 UTC. EXCEPT FOR THE STATIONS IN THE
FOPA20 KWNO MESSAGE...THE 12-H PROBABILITIES LABELED AS P12 ARE
VALID FOR PERIODS OF 12-24...24-36...36-48...48-60...AND 60-72
HOURS AFTER EITHER 0000 OR 1200 UTC. FOR THE FOPA20 KWNO
SITES...THE 12-H PROBABILITIES ARE VALID FOR PERIODS OF
6-18...18-30...30-42...42-54...AND 54-66 HOURS AFTER 0000 OR
1200 UTC. THE QPF GUIDANCE LABELED AS Q06 AND Q12...
RESPECTIVELY...FOR THE 6- AND 12-H PERIODS... PROVIDES
CATEGORICAL FORECASTS OF PRECIPITATION AMOUNT FOR THE SAME
PROJECTIONS AS THE POP. THE CATEGORICAL DEFINITIONS ARE:
0 = NO PRECIPITATION;
1 = 0.01 TO 0.09 INCHES;
2 = 0.10 TO 0.24 INCHES;
3 = 0.25 TO 0.49 INCHES;
4 = 0.50 TO 0.99 INCHES;
5 = > OR = 1.00 INCHES /Q06/; 1.00 - 1.99 INCHES /Q12/
6 = > OR = 2.00 INCHES /Q12 ONLY/
MORE DETAILS ON THE NEW GUIDANCE MAY BE FOUND AT THE FOLLOWING
SITES /USE LOWER CASE/:
HTTP://WWW.NWS.NOAA.GOV/TDL/SYNOP/MOS2000.HTM
HTTP://WWW.NWS.NOAA.GOV/OM/TPB/463.PDF
IN ADDITION TO THE NEW QPF GUIDANCE...WE UPDATED THE EQUATIONS
USED TO PRODUCE THE VISIBILITY AND OBSTRUCTION TO VISION GUIDANCE
AVAILABLE IN THE MAV MESSAGE. THIS UPDATE ELIMINATES SPURIOUS
FORECASTS OF LOW VISIBILITY CONDITIONS THAT HAD BEEN NOTED BY
SEVERAL FORECASTERS.
IF YOU HAVE ANY QUESTIONS ABOUT THESE CHANGES TO THE AVIATION MOS
GUIDANCE...PLEASE CONTACT:
NAME: PAUL DALLAVALLE
PHONE: 301-713-1065 EXT. 174
E-MAIL: PAUL.DALLAVALLE@xxxxxxxx
THIS AND OTHER NATIONAL TECHNICAL INFORMATION NOTICES ARE
AVAILABLE ON THE INTERNET AT /USE LOWER CASE/:
HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM
END
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