Tropical Storm PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 PM AST MON SEP 26 2011
 
THE CLOUD PATTERN HAS REMAINED ABOUT THE SAME SINCE THIS MORNING
WITH MOST OF THE DEEP CONVECTION OCCURRING OVER THE SOUTHERN
PORTION OF THE CIRCULATION AND WELL-DEFINED LOW CLOUD LINES OVER
THE NORTHERN SEMICIRCLE.  A BLEND OF DVORAK CURRENT INTENSITY
ESTIMATES FROM TAFB AND SAB GIVES 50 KT AGAIN FOR THE INITIAL WIND
SPEED ESTIMATE.  UPPER-LEVEL OUTFLOW IS STILL BEING IMPEDED OVER
THE NORTHWEST QUADRANT...AS PHILIPPE CONTINUES TO BE AFFECTED BY
MODERATE WESTERLY SHEAR.  THE STORM IS EXPECTED TO REMAIN OVER
MARGINALLY WARM WATERS AND ASSUMING THE SHEAR DOES NOT INCREASE TOO
MUCH...SOME SLIGHT STRENGTHENING IS POSSIBLE THROUGH TOMORROW. 
HOWEVER...SIGNIFICANT INTENSIFICATION SEEMS UNLIKELY AT THIS TIME. 
AS PHILIPPE MOVES FARTHER NORTH...WESTERLY WINDS ALOFT ARE EXPECTED
TO INCREASE AND THIS SHOULD CAUSE SOME WEAKENING TO COMMENCE BY 36
TO 48 HOURS.  THE OFFICIAL WIND SPEED FORECAST FOLLOWS THE RELIABLE
LGEM GUIDANCE.

THE FORWARD MOTION HAS SLOWED AND IS NOW NEAR 315/7.  DURING THE
NEXT FEW DAYS...THE TROPICAL CYCLONE IS EXPECTED TO MOVE AROUND THE
SOUTHWESTERN AND WESTERN PERIPHERY OF A SUBTROPICAL ANTICYCLONE
OVER THE EXTREME EASTERN ATLANTIC.  BY DAYS 3 TO 5...HOWEVER...THE
TRACK GUIDANCE SPLITS INTO 2 GENERAL CAMPS.  SOME MODELS SUCH AS
THE HWRF...GFDL...GFDN...AND NOGAPS TURN PHILIPPE SHARPLY
NORTHEASTWARD TO THE SOUTH OF A TROUGH OVER THE EASTERN ATLANTIC. 
OTHER MODELS SUCH AS THE GFS...ECMWF...AND UKMET HAVE THE CYCLONE
MISSING THE TROUGH AND BECOMING TRAPPED UNDER A SUBTROPICAL
RIDGE...RESULTING IN A GENERALLY WEST-NORTHWESTWARD MOTION.  GIVEN
THE WIDE RANGE OF POSSIBILITIES LATE IN THE FORECAST PERIOD...THE
OFFICIAL FORECAST SHOWS ONLY A SLOW NORTHWARD MOTION FROM 72 TO 120
HOURS AS A COURSE OF LEAST REGRET. 
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/2100Z 15.4N  34.4W   50 KT  60 MPH
 12H  27/0600Z 16.1N  35.2W   55 KT  65 MPH
 24H  27/1800Z 17.1N  36.2W   55 KT  65 MPH
 36H  28/0600Z 18.2N  37.2W   50 KT  60 MPH
 48H  28/1800Z 19.4N  38.3W   50 KT  60 MPH
 72H  29/1800Z 22.0N  40.0W   45 KT  50 MPH
 96H  30/1800Z 23.5N  40.0W   40 KT  45 MPH
120H  01/1800Z 24.5N  40.0W   35 KT  40 MPH
 
$$
FORECASTER PASCH
 
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