Tropical Storm SEAN

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TROPICAL STORM SEAN DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL192011
500 PM AST THU NOV 10 2011

SATELLITE IMAGES SHOW THAT THE STRUCTURE OF SEAN HAS BECOME A LITTLE
LESS ORGANIZED...WITH CONVECTION AROUND THE EYE FEATURE APPEARING
TO WEAKEN A BIT AND BECOME LESS SYMMETRIC. AN AIR FORCE RESERVE
AIRCRAFT MISSION THIS AFTERNOON INTO SEAN FOUND PEAK FLIGHT-LEVEL
WINDS OF 63 KT...SFMR MEASUREMENTS OF 52 KT...ALONG WITH A CENTRAL
PRESSURE OF 983 MB. THESE DATA SUPPORT MAINTAINING THE INTENSITY AT
55 KT. THE CHANCES OF SEAN BECOMING A HURRICANE APPEAR TO BE
DIMINISHING DUE TO THE DEGRADED STRUCTURE. SINCE THE MODELS
GENERALLY SHOW NO SIGNIFICANT INTENSIFICATION...THE INTENSITY
FORECAST WILL BE HELD AT 55 KT DURING THE SHORT-TERM PERIOD. BY
TOMORROW...WEAKENING IS LIKELY...AND THIS IS ALREADY BEING HERALDED
BY THE ERODING CIRRUS OVERFLOW ON THE NORTHWESTERN SIDE OF THE
CIRCULATION. THE NHC FORECAST IS REDUCED FROM THE PREVIOUS ONE...
AND IS SIMILAR TO THE MODEL CONSENSUS.

SEAN IS ACCELERATING TOWARD THE NORTHEAST...NOW MOVING AT ABOUT 
11 KT...ALTHOUGH RECENTLY IT MIGHT BE WOBBLING A LITTLE TO THE RIGHT
OF THAT ESTIMATE. THE MODEL GUIDANCE CONTINUES TO BE VERY
CONSISTENT IN SHOWING A NORTHEASTWARD ACCELERATION AS SEAN PASSES
TO THE NORTHWEST OF BERMUDA. THE LATEST MODEL SUITE HAS SHIFTED A
BIT TO THE SOUTHEAST...SO THE NHC TRACK FORECAST WAS BE NUDGED IN
THAT DIRECTION. IN A DAY OR SO...A COLD FRONT IS EXPECTED TO
OVERTAKE SEAN AND ABSORB THE SYSTEM. THE NEW FORECAST IS CONSISTENT
WITH THE LARGE-SCALE GUIDANCE...ALTHOUGH A FEW OF THE MODELS NOW
SHOW SEAN DISSIPATED AS EARLY AS 24 HOURS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/2100Z 30.9N  69.4W   55 KT  65 MPH
 12H  11/0600Z 32.5N  67.4W   55 KT  65 MPH
 24H  11/1800Z 36.1N  62.9W   50 KT  60 MPH
 36H  12/0600Z...ABSORBED
 
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FORECASTER BLAKE
 
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