[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 092042
TCDAT4

TROPICAL STORM SEAN DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL192011
400 PM EST WED NOV 09 2011

SATELLITE IMAGERY INDICATES THAT SEAN IS STRENGTHENING.  THE CLOUD
PATTERN CONSISTS OF A LARGE COILED BAND...WHICH APPEARS TO BE
WRAPPING UP INTO A BANDING EYE FEATURE.  DVORAK ESTIMATES ARE 55 KT
FROM BOTH TAFB/SAB...SO THIS WILL BE THE INITIAL WIND SPEED.  WITH
THE DEVELOPMENT OF THE CENTRAL CORE AND ABOUT A DAY OF LIGHT SHEAR
CONDITIONS REMAINING...FURTHER INTENSIFICATION SEEMS PROBABLE.  IT
IS A LITTLE PUZZLING WHY NONE OF THE MODELS MAKE THIS A HURRICANE...
ALTHOUGH THE INTENSITY GUIDANCE HAS GENERALLY HAD A LOW BIAS WITH
THIS SYSTEM.  GIVEN THE DEVELOPING EYE FEATURE...THE NEW NHC
FORECAST SHOWS SEAN REACHING HURRICANE STRENGTH...WHICH IS A BIT
HIGHER THAN THE SHIPS/LGEM MODELS.

THE STORM HAS TURNED TOWARD THE NORTH AT ABOUT 5 KT...A LITTLE
FASTER THAN EARLIER. A GRADUAL TURN TOWARD THE NORTHEAST WITH SOME
ACCELERATION IS EXPECTED TOMORROW AS THE TROPICAL CYCLONE FEELS THE
INFLUENCE OF A TROUGH MOVING INTO THE EASTERN UNITED STATES.
ALTHOUGH THERE IS STILL SOME SPREAD...THE GUIDANCE IS PRETTY
CONSISTENT IN SHOWING SEAN MOVING A FAIR DISTANCE TO THE NORTHWEST
OF BERMUDA. THE LATEST GFS/ECMWF MODELS CAME IN VERY CLOSE TO THE
PREVIOUS NHC FORECAST...AND ONLY SMALL CHANGES WERE MADE TO THE NEW
NHC TRACK. ALL OF THE GLOBAL MODELS SHOW SEAN BECOMING
EXTRATROPICAL IN TWO DAYS...AND THEN BEING ABSORBED BY A FRONTAL
BOUNDARY BY DAY 3.


FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 28.7N  70.5W   55 KT  65 MPH
 12H  10/0600Z 29.4N  70.5W   60 KT  70 MPH
 24H  10/1800Z 30.6N  69.5W   65 KT  75 MPH
 36H  11/0600Z 32.7N  67.0W   60 KT  70 MPH
 48H  11/1800Z 35.8N  62.7W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  12/1800Z...ABSORBED

$$
FORECASTER BLAKE



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