Hurricane TOMAS

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HURRICANE TOMAS DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
1100 AM AST SUN OCT 31 2010
 
DEEP CONVECTION ASSOCIATED WITH TOMAS HAS GENERALLY DECREASED DURING
THE LAST FEW HOURS AND BANDING FEATURES HAVE BECOME A LITTLE LESS
ORGANIZED. IN ADDITION...RECENT MICROWAVE IMAGES NO LONGER SHOW AN
EYE. BASED ON THIS...THE INITIAL WIND SPEED IS LOWERED TO 80
KT...WHICH IS A BLEND OF THE LATEST SUBJECTIVE AND OBJECTIVE
SATELLITE INTENSITY ESTIMATES. THE NEXT AIR FORCE RESERVE
RECONNAISSANCE AIRCRAFT SHOULD PROVIDE A BETTER ASSESSMENT OF THE
INTENSITY EARLY THIS AFTERNOON.
 
THE INITIAL MOTION ESTIMATE IS 285/8.  A GENERAL WESTWARD TO
WEST-NORTHWESTWARD MOTION AT ABOUT THE SAME SPEED IS EXPECTED
DURING THE NEXT COUPLE OF DAYS AS MID-LEVEL RIDGING REMAINS IN
PLACE TO THE NORTH OF TOMAS.  SOME OF THE MODELS EVEN SHOW A SOUTH
OF WEST MOTION DURING THAT TIME.  IN ABOUT 3 DAYS...THE CYCLONE IS
EXPECTED TO SLOW DOWN AS A LARGE MID- TO UPPER-LEVEL LOW MOVES OVER
THE GULF OF MEXICO...CAUSING THE RIDGE TO ERODE.  TOMAS IS FORECAST
TO GRADUALLY TURN TOWARD THE NORTH IN 4 TO 5 DAYS AS IT FEELS THE
INFLUENCE OF SOUTHERLY FLOW TO THE EAST OF THE TROUGH.  THE LATEST
MODEL GUIDANCE HAS CHANGED LITTLE FROM THE LAST CYCLE...AND THE
OFFICIAL FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS TRACK.
 
ALTHOUGH TOMAS LIES OVER AN AREA OF HIGH OCEANIC HEAT CONTENT...
MODERATE SOUTHWESTERLY SHEAR AND SOME MID-LEVEL DRY AIR AS SHOWN BY
MODEL CROSS SECTIONS COULD BE A LIMITING FACTOR FOR INTENSIFICATION
DURING THE NEXT COUPLE OF DAYS.  IN FACT...SEVERAL OF THE RELIABLE
MODELS...INCLUDING THE GFS...ECMWF...AND GFDL...SHOW THE VORTEX
TILTING TO THE NORTHEAST WITH HEIGHT.  THIS RESULTS IN THE
WEAKENING OF THE HURRICANE IN THOSE MODELS DURING THE NEXT COUPLE
OF DAYS.  THE OFFICIAL FORECAST HAS BEEN NUDGED DOWNWARD THROUGH 48
HOURS BUT REMAINS HIGHER THAN ALL OF THE INTENSITY GUIDANCE DURING
THAT TIME. A MORE FAVORABLE UPPER-LEVEL WIND PATTERN IS EXPECTED
DURING THE 3 TO 5 DAY TIME FRAME...AND THAT SHOULD ALLOW FOR STEADY
STRENGTHENING.
 
ALTHOUGH TROPICAL STORM WARNINGS FOR THE WINDWARD ISLANDS HAVE BEEN
DISCONTINUED...THE THREAT OF HEAVY RAINFALL IS EXPECTED TO CONTINUE
OVER MUCH OF THE LESSER ANTILLES THROUGH TONIGHT.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/1500Z 14.0N  63.7W    80 KT
 12HR VT     01/0000Z 14.5N  65.1W    75 KT
 24HR VT     01/1200Z 14.9N  67.2W    75 KT
 36HR VT     02/0000Z 15.0N  69.1W    75 KT
 48HR VT     02/1200Z 15.0N  70.6W    75 KT
 72HR VT     03/1200Z 15.0N  72.5W    85 KT
 96HR VT     04/1200Z 15.5N  73.5W    95 KT
120HR VT     05/1200Z 17.0N  73.5W   100 KT
 
$$
FORECASTER CANGIALOSI/BROWN
 
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