[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 110236
TCDAT4

TROPICAL STORM SEAN DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL192011
1100 PM AST THU NOV 10 2011

SATELLITE TRENDS HAVE PROVIDED MIXED SIGNALS REGARDING THE INTENSITY
OF SEAN OVER THE PAST FEW HOURS. ON ONE HAND...VERTICAL SHEAR OF
ABOUT 20 KT AS ANALYZED BY UW-CIMSS HAS DISPLACED THE MID-LEVEL
CENTER EAST OF THE LOW-LEVEL CENTER...AS SEEN IN RECENT MICROWAVE
IMAGERY FROM THE FNMOC TC WEBPAGE. HOWEVER...CONVECTIVE CLOUD TOPS
HAVE COOLED AND EXPANDED IN COVERAGE OVER THE PAST FEW HOURS.
THEREFORE...THE INITIAL INTENSITY WILL BE HELD AT 55 KT IN
AGREEMENT WITH 00Z DVORAK CI-NUMBERS FROM TAFB AND SAB. THE NHC
FORECAST SHOWS NO CHANGE IN INTENSITY DURING THE NEXT 12 HOURS...IN
AGREEMENT WITH MOST OF THE GUIDANCE. BY 24 HOURS...SEAN SHOULD BE
ABSORBED BY THE FRONTAL BOUNDARY NOW MOVING OFFSHORE OF THE EAST
COAST OF THE UNITED STATES.

RECENT DVORAK AND MICROWAVE FIXES SUGGEST THAT THE LOW-LEVEL CENTER
HAS BEEN MOVING A BIT TO THE RIGHT OF THE PREVIOUS FORECAST...WITH
AN INITIAL MOTION OF 060/11. THIS RIGHTWARD JOG SHOULD BE TEMPORARY
HOWEVER...AS ALL OF THE GUIDANCE SHOWS A NORTHEASTWARD MOTION
DEVELOPING OVERNIGHT AS THE DEEP-LAYER FLOW BECOMES SOUTHWESTERLY
AHEAD OF THE MID/UPPER-LEVEL TROUGH MOVING OFF THE U.S. EAST COAST.
GIVEN THE INITIAL POSITION AND MOTION...THE NEW NHC TRACK FORECAST
HAS BEEN ADJUSTED TO THE RIGHT...OR SOUTHEAST...OF THE PREVIOUS
ONE...AND LIES A LITTLE TO THE RIGHT OF THE GFS AND ECMWF AND CLOSE
TO THE GEFS ENSEMBLE MEAN.


FORECAST POSITIONS AND MAX WINDS

INIT  11/0300Z 31.5N  68.2W   55 KT  65 MPH
 12H  11/1200Z 33.6N  65.3W   55 KT  65 MPH
 24H  12/0000Z...ABSORBED BY FRONT

$$
FORECASTER BRENNAN


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