Tropical Storm PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER  28
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
1100 PM AST FRI SEP 30 2011
 
A PAIR OF MICROWAVE PASSES FROM LATE THIS AFTERNOON WERE VERY
HELPFUL IN FIXING THE CENTER OF PHILIPPE AFTER THE CENTER BECAME
OBSCURED...AND INDICATED THE CYCLONE WAS A LITTLE TO THE RIGHT OF
THE PREVIOUS TRACK.  THE INITIAL MOTION IS 320/8.  THE MICROWAVE
DATA ALSO SHOWED A VERY WELL-DEFINED LOW-LEVEL CONVECTIVE
RING...BUT THE CURRENT INFRARED DEPICTION SUGGESTS THAT UPPER-LEVEL
NORTHWESTERLY FLOW FROM OPHELIA IS BEGINNING TO TAKE A TOLL. 
DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB WERE 45 AND 35
KT...RESPECTIVELY...AND THE ADVISORY INTENSITY IS HELD AT 45 KT.

WATER VAPOR IMAGERY AND GLOBAL MODEL FORECASTS SUGGEST THAT THE
NORTHWESTERLY SHEAR WILL LIKELY EXCEED 40 KT OVER THE NEXT COUPLE
OF DAYS...SUCH THAT PHILIPPE COULD WELL SUFFER A BEHEADING AT THE
HANDS OF OPHELIA.  THE LGEM...TRADITIONALLY THE BEST INTENSITY
GUIDANCE...SHOWS A SLOW DECREASE IN STRENGTH AND THE OFFICIAL
FORECAST IS IN GOOD AGREEMENT WITH THIS MODEL.  THE REMAINING
GUIDANCE IS INEXPLICABLY INDIFFERENT TO THE SHEAR AND SHOWS LITTLE
NET CHANGE IN STRENGTH.  NEAR THE END OF THE FORECAST PERIOD...
SHOULD PHILIPPE SURVIVE...THE SHEAR IS EXPECTED TO LESSEN
AND SO THE OFFICIAL FORECAST SHOWS A LITTLE STRENGTHENING AT THAT
TIME. 

A MID-LEVEL RIDGE IN BETWEEN THE TWO TROPICAL CYCLONES IS EXPECTED
TO TURN PHILIPPE TO THE WEST-NORTHWEST AND PERHAPS WEST OVER THE
NEXT COUPLE OF DAYS.  HOWEVER...THE STRENGTH OF THIS TURN WILL
DEPEND ON HOW MUCH CONVECTION PHILIPPE CAN MAINTAIN AS THE
NORTHWESTERLY SHEAR INCREASES...WITH A WEAKER OR SHALLOWER SYSTEM
MAINTAINING A NORTHWARD COMPONENT OF MOTION LONGER.  BY DAY
FOUR...PHILIPPE SHOULD BE APPROACHING A LARGE TROUGH OFF THE U.S.
EAST COAST AND TURN NORTHWARD.  MODEL GUIDANCE DIVERGES
SIGNIFICANTLY AT THAT POINT...WITH THE ECMWF AND UKMET SHOWING
PHILIPPE TURNING NORTHEASTWARD AND THE GFS MUCH FARTHER SOUTHWEST. 
THE OFFICIAL FORECAST HAS BEEN ADJUSTED TO THE RIGHT OF THE
PREVIOUS FORECAST TOWARDS THE ECMWF AND SHALLOW BAM...UNDER THE
ASSUMPTION THAT PHILIPPE WILL NOT BE ABLE TO MAINTAIN MUCH VERTICAL
COHERENCE OVER THE NEXT TWO TO THREE DAYS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0300Z 24.0N  46.4W   45 KT  50 MPH
 12H  01/1200Z 24.7N  47.5W   45 KT  50 MPH
 24H  02/0000Z 25.5N  49.4W   40 KT  45 MPH
 36H  02/1200Z 26.1N  51.5W   40 KT  45 MPH
 48H  03/0000Z 26.5N  53.4W   35 KT  40 MPH
 72H  04/0000Z 27.0N  57.5W   30 KT  35 MPH
 96H  05/0000Z 28.0N  60.0W   30 KT  35 MPH
120H  06/0000Z 31.0N  60.0W   35 KT  40 MPH
 
$$
FORECASTER FRANKLIN
 
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