[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 101432
TCDAT4

TROPICAL STORM SEAN DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL192011
1000 AM EST THU NOV 10 2011

THERE HAS NOT BEEN MUCH CHANGE WITH SEAN OVER THE PAST SEVERAL
HOURS. THE STORM CONTINUES TO SHOW A RAGGED EYE...WITH A MORE
COMPACT APPEARANCE ON SATELLITE THAN YESTERDAY. DVORAK ESTIMATES
REMAIN THE SAME...SO THE INITIAL WIND SPEED WILL REMAIN AT 55 KT.
AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO BE IN
THE CYCLONE AROUND 1800 UTC TO PROVIDE A BETTER ESTIMATE OF THE
INITIAL WINDS. SEAN STILL HAS A DAY OR SO OF MARGINAL WATER
TEMPERATURES AND MODERATE SHEAR LEFT TO INTENSIFY. SOUTHWESTERLY
SHEAR SHOULD NOTABLY INCREASE AFTER THAT TIME...WHICH SHOULD CAUSE
WEAKENING OF THE STORM. MODEL GUIDANCE IS A LITTLE LOWER THAN SIX
HOURS AGO...AND THE NHC FORECAST IS REDUCED FROM THE PREVIOUS ONE.
SEAN COULD STILL BECOME A HURRICANE...ALTHOUGH IT IS NOT EXPLICITLY
FORECAST.

THE STORM HAS MADE THE TURN TO THE NORTHEAST...MOVING ABOUT 035/6.
GUIDANCE IS IN GOOD AGREEMENT ON THIS TRACK CONTINUING WITH A
SIGNIFICANT INCREASE IN FORWARD SPEED BY FRIDAY MORNING DUE TO AN
APPROACHING MID-LATITUDE TROUGH.  THE NEW FORECAST IS BASICALLY AN
UPDATE OF THE PREVIOUS ONE...SHOWING THE CYCLONE PASSING A FAIR
DISTANCE NORTHWEST OF BERMUDA.  STRONG SHEAR...COOLER WATERS...AND
A COLD FRONT ARE EXPECTED TO CAUSE EXTRATROPICAL TRANSITION IN
ABOUT 36 HOURS...WITH SEAN BECOMING ABSORBED BY THAT FRONT WITHIN
48 HOURS.  IT WOULD NOT BE SURPRISING IF SEAN DISSIPATED A LITTLE
FASTER THAN SHOWN BELOW...AS INDICATED BY THE GFS AND UKMET MODELS.


FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 30.4N  70.5W   55 KT  65 MPH
 12H  11/0000Z 31.8N  69.0W   60 KT  70 MPH
 24H  11/1200Z 34.7N  65.6W   60 KT  70 MPH
 36H  12/0000Z 39.0N  60.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  12/1200Z...ABSORBED

$$
FORECASTER BLAKE


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