[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 060240
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  48
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
1100 PM AST WED OCT 05 2011

PHILIPPE HAS CHANGED LITTLE IN ORGANIZATION DURING THE PAST SEVERAL
HOURS.  THE LOW-LEVEL CENTER IS LOCATED NEAR THE WESTERN EDGE OF
THE CENTRAL CONVECTION...WHILE AN OUTER CONVECTIVE BAND IS PRESENT
IN THE EASTERN SEMICIRCLE.  SATELLITE INTENSITY ESTIMATES REMAIN 65
KT FROM TAFB AND 55 KT FROM SAB...SO THE INITIAL INTENSITY REMAINS
55 KT.  ANALYSES FROM THE SHIPS MODEL AND CIMSS AT THE UNIVERSITY
OF WISCONSIN SHOW THAT THE VERTICAL WIND SHEAR HAS DECREASED TO
ABOUT 10 KT.

THE INITIAL MOTION IS NOW 010/6.  PHILIPPE IS RECURVING TO THE EAST
OF A DEEP-LAYER TROUGH AND ASSOCIATED SURFACE COLD FRONT OVER THE
WESTERN ATLANTIC...AND THE TRACK GUIDANCE IS NOW IN GOOD AGREEMENT
THAT THE CYCLONE WILL MOVE GENERALLY NORTHEASTWARD WITH SOME
ACCELERATION DURING THE NEXT 5 DAYS.  A MORE NORTHERLY MOTION MAY
OCCUR AFTER 72 HOURS AS THE CYCLONE BECOMES EXTRATROPICAL AND
MERGES WITH THE DEEP-LAYER TROUGH...AND THIS IS REFLECTED IN THE
FORECAST TRACK.  THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS
TRACK AND LIES IN THE MIDDLE OF THE TRACK GUIDANCE ENVELOPE.

WHILE PHILIPPE HAS NOT YET STRENGTHENED...THERE WILL BE A 12-24 HOUR
PERIOD OF LIGHT TO MODERATE SHEAR BEFORE THE CYCLONE ENCOUNTERS THE
STRONGER WESTERLIES TO THE NORTH.  FOR THE MOST PART...THE
INTENSITY GUIDANCE STILL CALLS FOR PHILIPPE TO BECOME A HURRICANE
DURING THAT TIME...AND SO DOES THE INTENSITY FORECAST.  AFTER 24
HOURS...INCREASING SHEAR SHOULD CAUSE A WEAKENING TREND.
EXTRATROPICAL TRANSITION SHOULD BEGIN IN ABOUT 48 HOURS AND BE
COMPLETE BY 72 HOURS.  THE DYNAMICAL MODELS AGREE ON PHILIPPE
MAINTAINING GALE TO STORM INTENSITY AS AN EXTRATROPICAL LOW...AND
THIS IS REFLECTED IN THE INTENSITY FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 26.4N  61.0W   55 KT  65 MPH
 12H  06/1200Z 27.4N  60.4W   60 KT  70 MPH
 24H  07/0000Z 28.5N  58.8W   65 KT  75 MPH
 36H  07/1200Z 29.3N  56.5W   60 KT  70 MPH
 48H  08/0000Z 30.8N  53.1W   55 KT  65 MPH
 72H  09/0000Z 37.0N  45.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  10/0000Z 43.5N  41.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  11/0000Z 52.0N  33.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BEVEN



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