Hurricane PHILIPPE

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TROPICAL STORM PHILIPPE DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU SEP 22 2005
 
PHILIPPE REMAINS VERY DISORGANIZED...WITH THE DEEP CONVECTION IN
SCATTERED CLUSTERS NEAR/AROUND THE ESTIMATED CENTER AND LITTLE
EVIDENCE OF BANDING FEATURES.  MY BEST GUESS IS THAT THE SYSTEM HAS
WEAKENED TO A MINIMAL TROPICAL STORM.  SHEARING AND SUBSIDENCE
ASSOCIATED WITH A LARGE UPPER-LEVEL LOW CENTERED NEAR 23N 62W HAVE
BEEN DISRUPTING THE TROPICAL CYCLONE.  GLOBAL MODELS CONTINUE TO
FORECAST THAT THE UPPER-LEVEL LOW WILL BE SQUEEZED INTO A CYCLONIC
SHEAR AXIS...CREATING AN ANTICYCLONIC UPPER-LEVEL FLOW FIELD OVER
PHILIPPE THAT WOULD ALLOW STRENGTHENING.  HOWEVER I SEE NO SIGN OF
THIS HAPPENING WITHIN THE NEXT DAY OR SO...AND THEREFORE NO CHANGE
IN STRENGTH IS FORECAST FOR 24 HOURS WITH ONLY A MODEST INCREASE IN
INTENSITY THEREAFTER.  ANOTHER POSSIBILITY IS THAT...GIVEN ITS
SOMEWHAT SUBTROPICAL APPEARANCE...THE SYSTEM COULD STRENGTHEN AS A
HYBRID-TYPE OF CYCLONE.  ASSUMING THAT PHILIPPE WILL INTERACT WITH
A FRONTAL SYSTEM BY THE END OF THE PERIOD...THE FORECAST SHOWS
EXTRATROPICAL TRANSFORMATION BY DAY 5.

THE CENTER CANNOT BE IDENTIFIED WITH GEOSTATIONARY IMAGERY...AND I
HAVE BASED THE LOCATION PRIMARILY ON A POOR FIX USING AN AMSU-B
IMAGE.  A RECENT AMSR-E IMAGE SUGGESTS THAT THE CENTER MAY BE
LOCATED MORE TO THE NORTHEAST...BUT WE WILL WAIT FOR VISIBLE
IMAGERY TO CONFIRM THIS.  FOR THE TIME BEING...THE INITIAL MOTION
ESTIMATE IS A HIGHLY UNCERTAIN 350/10.  TRACK GUIDANCE CONTINUES TO
INDICATE A MOTION AROUND THE WESTERN PERIPHERY OF A SUBTROPICAL
HIGH PRESSURE CELL.  THERE CONTINUES TO BE SOME UNCERTAINTY AS TO
WHETHER PHILIPPE WILL BE PICKED UP BY A SHORTWAVE TROUGH MOVING OFF
THE CANADIAN MARITIMES.  SOME GLOBAL MODELS...E.G. THE GFS...
INDICATE THAT AT LEAST A PIECE OF PHILIPPE'S VORTICITY WILL BE LEFT
BEHIND IN THE SUBTROPICS.  BECAUSE OF THIS UNCERTAINTY...THE
OFFICIAL TRACK FORECAST IS A LITTLE SLOWER AND TO THE RIGHT OF THAT
FROM THE PREVIOUS ADVISORY.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 23.3N  57.2W    35 KT
 12HR VT     22/1800Z 25.5N  57.8W    35 KT
 24HR VT     23/0600Z 28.1N  59.0W    35 KT
 36HR VT     23/1800Z 30.5N  60.0W    40 KT
 48HR VT     24/0600Z 32.5N  59.0W    45 KT
 72HR VT     25/0600Z 35.0N  54.0W    45 KT
 96HR VT     26/0600Z 37.0N  48.0W    40 KT
120HR VT     27/0600Z 38.5N  41.5W    40 KT...EXTRATROPICAL
 
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