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...FOR INTERGOVERNMENTAL USE ONLY...
TROPICAL STORM SEBASTIEN DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SUN OCT 22 1995

THE STORM REMAINS IN AN ENVIRONMENT OF SOUTHWESTERLY VERTICAL SHEAR.
BURSTS OF STRONG CONVECTION HAVE BEEN OBSERVED NEAR THE ESTIMATED
CENTER...AND ANALYSIS OF SATELLITE IMAGES SUGGESTS THAT THE
INTENSITY REMAINS NEAR 35 KNOTS.  LATEST AVN MODEL FORECAST SUGGESTS
WEAKER UPPER-LEVEL FLOW BETWEEN 60W AND 70W...SOUTH OF 25N...DURING
THE NEXT DAY OR TWO.  THUS IF SEBASTIEN TURNS WESTWARD IT MIGHT BE
ABLE TO STRENGTHEN IN THE SHORT TERM.  BEYOND 36 TO 48 HOURS...THE
AVN FORECAST INDICATES INCREASING UPPER-LEVEL FLOW FROM THE
NORTHWEST OVER MOST OF THE AREA EAST OF 65W NORTH OF 22N...WHICH
WOULD WEAKEN THE STORM ESPECIALLY IF IT MOVES NORTH TO NORTHWEST. 
GIVEN THE UNCERTAINTIES IN HOW THE UPPER WINDS WILL EVOLVE IN THE
ENVIRONMENT OF SEBASTIEN...NO CHANGE IN STRENGTH IS FORECAST.

THERE HAS APPARENTLY BEEN SOME SLOWING OF THE FORWARD MOTION... AND
CURRENT MOVEMENT IS ESTIMATED TO BE 350/10.  SEBASTIEN IS EXPECTED
TO TURN TO THE NORTHWEST DURING THE NEXT 24 HOURS UNDER THE
INFLUENCE OF A LOW- TO MID-LEVEL CYCLONIC CIRCULATION CENTERED TO
THE WEST-SOUTHWEST...AND RISING SURFACE PRESSURES TO THE NORTH AND
NORTHWEST.  LATEST GFDL MODEL OUTPUT SHOWS A TURN TO THE WEST...THEN
WEST-NORTHWEST...WHEREAS THE MEDIUM BAM FORECASTS A NORTHWESTWARD
MOTION.  THE CURRENT OFFICIAL FORECAST IS BETWEEN THESE TWO TRACKS
BUT A LITTLE SLOWER...AND SLIGHTLY TO THE LEFT OF THE PREVIOUS NHC
FORECAST.

PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/0900Z 22.4N  56.8W    35 KTS
12HR VT     22/1800Z 23.5N  57.0W    35 KTS
24HR VT     23/0600Z 24.5N  58.0W    35 KTS
36HR VT     23/1800Z 25.0N  59.2W    35 KTS
48HR VT     24/0600Z 25.3N  60.5W    35 KTS
72HR VT     25/0600Z 26.0N  63.0W    35 KTS
 
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