[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 292039
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  23
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 PM AST THU SEP 29 2011

PHILIPPE HAS BEEN A CONUNDRUM TODAY.  THE LOW-LEVEL CIRCULATION HAS
BEEN ELONGATED FOR MUCH OF THE DAY...AND RECENT MICROWAVE
OVERPASSES HAVE SHOWN A WELL-DEFINED MID-LEVEL EYE WELL TO THE
NORTH OF THE PREVIOUSLY ESTIMATED CENTER.  IT APPEARS THAT THE
LOW-LEVEL CENTER IS REFORMING FARTHER NORTH...BUT IT IS NOT YET
CERTAIN HOW MUCH IT IS TUCKED UNDER THE DEEP CONVECTION.  BECAUSE
OF THE UNCERTAINTY IN CENTER LOCATION...DVORAK INTENSITY ESTIMATES
RUN THE GAMUT FROM 35 TO 55 KT.  THE INITIAL INTENSITY IS HELD AT
40 KT...BUT THAT COULD BE CONSERVATIVE ESPECIALLY IF THE CENTER
CONTINUES TO REFORM OR GET PULLED FARTHER NORTH INTO THE
CONVECTION.  PHILIPPE HAS ABOUT 24 HOURS TO STRENGTHEN BEFORE
NORTHERLY VERTICAL SHEAR INCREASES.  HOWEVER...THE INTENSITY MODELS
SUGGEST THAT PHILIPPE WILL BE ABLE TO WITHSTAND THE HOSTILE
CONDITIONS AND THUS ONLY SHOW GRADUAL WEAKENING AFTER 48 HOURS.
THE OFFICIAL FORECAST FOLLOWS THAT SCENARIO AND KEEPS PHILIPPE AS A
TROPICAL CYCLONE FOR THE ENTIRE FORECAST PERIOD.

GIVEN THE CENTER RELOCATION...THE INITIAL MOTION IS AN UNCERTAIN 310
DEGREES AT 11 KT.  THERE HAS BEEN NO CHANGE IN THE FORECAST TRACK
REASONING.  PHILIPPE WILL CONTINUE TO BE STEERED NORTHWESTWARD FOR
THE NEXT DAY OR SO AND THEN TURN WESTWARD BY DAY 3 AS IT COMES
UNDER THE INFLUENCE OF A BUILDING RIDGE TO THE NORTH.  THE WESTWARD
MOTION SHOULD CONTINUE THROUGH DAY 5...ESPECIALLY AS PHILIPPE
BECOMES A WEAKER SYSTEM AS IS STEERED BY THE LOW-LEVEL EASTERLY
FLOW.  THE TRACK GUIDANCE IS IN FAIRLY GOOD AGREEMENT...AND THERE
ARE REALLY NO OUTLIERS IN THE SUITE OF MODELS.  THEREFORE...LITTLE
CHANGE WAS REQUIRED TO THE OFFICIAL FORECAST COMPARED WITH THE
PREVIOUS ONE.

FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 20.2N  43.6W   40 KT  45 MPH
 12H  30/0600Z 21.4N  44.8W   45 KT  50 MPH
 24H  30/1800Z 22.8N  46.6W   45 KT  50 MPH
 36H  01/0600Z 23.8N  48.5W   45 KT  50 MPH
 48H  01/1800Z 24.5N  50.2W   45 KT  50 MPH
 72H  02/1800Z 25.0N  54.0W   40 KT  45 MPH
 96H  03/1800Z 25.0N  58.5W   35 KT  40 MPH
120H  04/1800Z 24.5N  62.0W   35 KT  40 MPH

$$
FORECASTER BERG


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