Tropical Storm PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER  43
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 PM AST TUE OCT 04 2011
 
THE STRUCTURE OF PHILIPPE HAS CHANGED LITTLE OVER THE PAST FEW HOURS
WITH THE LOW-LEVEL CENTER LOCATED NEAR THE NORTHERN EDGE OF THE
DEEP CONVECTION.  ALTHOUGH DVORAK FINAL-T NUMBERS FROM TAFB AND SAB
HAVE FALLEN TO 45 KT...AN ASCAT PASS FROM 1410 UTC SHOWED A FEW 50
KT BARBS IN THE CONVECTION TO THE EAST OF THE CENTER.  THE
INTENSITY IS THEREFORE HELD AT 55 KT.  

GLOBAL MODEL FIELDS SUGGEST THAT THE STRONG NORTHERLY SHEAR WHICH
HAS BEEN AFFECTING PHILIPPE FOR THE PAST 4 DAYS SHOULD ABATE IN THE
NEXT 24 HOURS...LEAVING THE CYCLONE IN A FAVORABLE BUT SMALL REGION
OF UPPER-LEVEL RIDGING.  THIS SHOULD ALLOW FOR SOME
STRENGTHENING...AND THE OFFICIAL FORECAST CONTINUES TO SHOW
PHILIPPE BECOMING A HURRICANE IN THE 36-48 HOUR TIME FRAME.  STRONG
SOUTHWESTERLY SHEAR IS THEN EXPECTED TO DEVELOP OVER PHILIPPE AFTER
48 HOURS...YET FOR THE MOST PART THE INTENSITY MODELS DO NOT SHOW
MUCH WEAKENING.  THE ONE EXCEPTION IS THE LGEM...WHICH TENDS TO
HANDLE SHEAR BETTER THAN THE OTHER MODELS TOWARD THE LATTER PART OF
THE FORECAST PERIOD AND IS AT THE LOWER END OF THE GUIDANCE AT THIS
TIME.  THE OFFICIAL FORECAST IS VERY CLOSE TO THE MODEL CONSENSUS
FOR MOST OF THE PERIOD...AND IT IS HIGHER THAN THE LGEM AT DAY 5
DUE TO THE POSSIBILITY OF SOME BAROCLINIC FORCING AS PHILIPPE
BECOMES EXTRATROPICAL.  

THE LOW-LEVEL CENTER HAS BECOME A LITTLE DIFFICULT TO LOCATE THIS
AFTERNOON...BUT THE LOW-CLOUD LINES SUGGEST TO ME THAT IT HAS
EITHER JUMPED TO THE NORTH...OR THE LOW-LEVEL CIRCULATION IS
BECOMING SOMEWHAT ELONGATED.  REGARDLESS...PHILIPPE HAS AN AVERAGED
INITIAL MOTION OF 280 DEGREES AT 9 KT AND IS ABOUT START ITS SHARP
RE-CURVATURE.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT AT LEAST FOR
THE FIRST 72 HOURS...BUT AS HAS BEEN THE CASE FOR SEVERAL DAYS
NOW...THE ECMWF IS ON THE EASTERN AND SOUTHERN SIDE OF THE GUIDANCE
WHILE THE GFS IS FARTHER WEST AND NORTH.  THE ECMWF ALSO APPEARS TO
DIFFER FROM THE OTHER GLOBAL MODELS BY HAVING PHILIPPE STAY FARTHER
SOUTH AND BE ABSORBED BY A COLD FRONT WHEREAS THE OTHER MODELS SHOW
IT BECOMING THE MAIN THE PARENT CYCLONE OF THE FRONTAL SYSTEM.  THE
NEW OFFICIAL FORECAST IS SHIFTED A BIT TO THE EAST OF THE PREVIOUS
ONE FOR THE FIRST 48 HOURS BUT IS THEN VERY SIMILAR ON DAYS 3
THROUGH 5...FOLLOWING THE IDEA THAT PHILIPPE WILL BE MOVING
NORTHEASTWARD AS AN EXTRATROPICAL CYCLONE ON DAY 5.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/2100Z 24.1N  60.0W   55 KT  65 MPH
 12H  05/0600Z 24.5N  61.1W   55 KT  65 MPH
 24H  05/1800Z 25.2N  61.7W   60 KT  70 MPH
 36H  06/0600Z 26.3N  61.7W   65 KT  75 MPH
 48H  06/1800Z 27.3N  60.8W   65 KT  75 MPH
 72H  07/1800Z 29.5N  57.0W   60 KT  70 MPH
 96H  08/1800Z 32.0N  50.5W   55 KT  65 MPH
120H  09/1800Z 36.5N  46.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 
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FORECASTER BERG
 
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