Tropical Storm DEBBY

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TROPICAL STORM DEBBY DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042006
1100 PM EDT THU AUG 24 2006
 
DEBBY STILL LOOKS MUCH LIKE IT DID SIX HOURS AGO...WITH A RELATIVELY
SMALL AREA OF DEEP CONVECTION AND CIRRUS SPREADING OUT TO THE NORTH
DUE TO SOUTHERLY SHEAR.  DVORAK DATA-T NUMBERS HAVE NOT CHANGED AND
THE CURRENT INTENSITY ESTIMATES ARE 30-35 KT.  HOWEVER...THE
STRONGEST WINDS RETRIEVED BY QUIKSCAT IN AN OVERPASS AROUND 21Z
WERE 45 KT...AND THAT REMAINS THE ADVISORY INTENSITY.  MANUAL
ANALYSIS OF THE QUIKSCAT DIRECTIONAL AMBIGUITIES CONFIRMS THAT THE
LOW-LEVEL CIRCULATION CENTER REMAINS BENEATH THE SOUTHERN PORTIONS
OF THE MASS OF DEEP CONVECTION.  THE INITIAL MOTION OF 295/16 IS
JUST A LITTLE LEFT OF WHAT IT WAS EARLIER...BUT STILL
WEST-NORTHWESTWARD.

ONCE AGAIN THERE IS LITTLE CHANGE TO THE FORECAST OR THE UNDERLYING
REASONING.  THE STEERING MECHANISMS LEADING TO RECURVATURE REMAIN
FAIRLY STRAIGHTFORWARD...AND THE OFFICIAL TRACK FORECAST IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS ADVISORY AND REMAINS CLOSE TO
THE CONSENSUS OF THE TIGHTLY-CLUSTERED DYNAMICAL MODEL GUIDANCE. 
THE SOUTHERLY SHEAR WILL PROBABLY NOT ABATE MUCH DURING THE NEXT
COUPLE OF DAYS DUE TO A PERSISTENT MID- TO UPPER-LEVEL TROUGH TO
THE WEST OF DEBBY...SO ONLY VERY GRADUAL STRENGTHENING IS FORECAST
DURING THAT PERIOD.  THE UPPER-LEVEL WINDS MIGHT SLACKEN A BIT ON
DAY 3 AND ALLOW DEBBY TO STRENGTHEN A LITTLE FASTER...BUT
THEREAFTER A MID-LATITUDE TROUGH TRAVERSING THE NORTH-CENTRAL
ATLANTIC WILL AGAIN INCREASE THE SHEAR.  THE CHANCES OF DEBBY
REACHING HURRICANE INTENSITY BEFORE EXTRATROPICAL TRANSITION APPEAR
TO BE QUITE MARGINAL...AND THE NEW OFFICIAL INTENSITY FORECAST IS
NUDGED DOWNWARD SLIGHTLY ON DAYS 4 AND 5...VERY CLOSE TO THE SHIPS
GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0300Z 21.9N  41.1W    45 KT
 12HR VT     25/1200Z 22.9N  43.4W    45 KT
 24HR VT     26/0000Z 24.6N  46.2W    45 KT
 36HR VT     26/1200Z 26.2N  48.5W    50 KT
 48HR VT     27/0000Z 28.1N  50.2W    55 KT
 72HR VT     28/0000Z 32.0N  51.0W    55 KT
 96HR VT     29/0000Z 36.0N  48.0W    60 KT
120HR VT     30/0000Z 41.0N  42.0W    60 KT...EXTRATROPICAL
 
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FORECASTER KNABB
 
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