[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 201454
TCDAT2
HURRICANE PHILIPPE DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT TUE SEP 20 2005

THE CENTER OF PHILIPPE WAS VERY DIFFICULT TO LOCATE OVERNIGHT.
EARLY MORNING SATELLITE AND MICROWAVE DATA HELPED TO DETERMINE THAT
THE CENTER WAS LOCATED TO THE WEST OF THE DEEP CONVECTION. WESTERLY
SHEAR HAS CONTINUED TO TAKE ITS TOLL ON THE HURRICANE...AND WITHIN
THE LAST HOUR OR TWO THE LOW LEVEL CENTER HAS BECOME EXPOSED.
THIS HAS RESULTED IN A RELOCATION OF THE CENTER AND A WESTWARD
ADJUSTMENT TO THE TRACK FORECAST DURING THE FIRST 24-36 HOURS.
CURRENT DVORAK DATA T NUMBERS SUPPORT AROUND 55 KT.  HOWEVER...THE
INITIAL INTENSITY FOR THIS ADVISORY WILL BE LOWERED TO 65 KT BASED
A BLEND OF THE LATEST DVORAK DATA T AND CURRENT INTENSITY NUMBERS.
THIS INTENSITY COULD BE A BIT GENEROUS BUT IT IS BETTER TO WAIT TO
SEE IF THE WEAKENING TREND CONTINUES BEFORE DOWNGRADING PHILIPPE.

THIS TRACK FORECAST CONTAINS HIGHER THAN NORMAL UNCERTAINTY AND
ASSUMES THAT PHILIPPE WILL REMAIN A DEEP SYSTEM. THE FORECAST
REASONING REMAINS BASICALLY UNCHANGED WITH PHILIPPE EXPECTED TO
MOVE NORTHWARD INTO A WEAKNESS IN THE SUBTROPICAL RIDGE...THEN
ACCELERATE NORTH THEN NORTHEASTWARD AHEAD OF A MID-LATITUDE TROUGH
IN 4-5 DAYS. IF THE CURRENT WESTERLY SHEAR DOES NOT RELAX AS
EXPECTED AND PHILIPPE WEAKENS...IT COULD TRACK FURTHER WESTWARD
AND ADDITIONAL ADJUSTMENTS TO THE TRACK WOULD BE NEEDED.

DUE TO THE CURRENT SATELLITE APPEARENCE...THE INTENSITY FORECAST
WEAKENS PHILIPPE TO A TROPICAL STORM IN 12 HOURS. THE SHIPS
INTENSITY MODEL CONTINUES TO RELAX THE WESTERLY SHEAR IN 12-24
HOURS AND THE OFFICIAL INTENSITY FORECAST SHOWS SLIGHT
RESTRENGTHENING THEREAFTER.  THE OFFICIAL FORECAST IS MUCH MORE
CONSERVATIVE THAN BOTH SHIPS AND GFDL.  IF PHILIPPE SURVIVES....
THE SHEAR IS FORECAST TO INCREASE AGAIN IN ABOUT 72 HOURS AND THIS
SHOULD GRADUALLY WEAKEN THE CYCLONE.

FORECASTER BROWN/AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL      20/1500Z 18.3N  57.1W    65 KT
 12HR VT     21/0000Z 18.8N  57.3W    60 KT
 24HR VT     21/1200Z 20.7N  57.8W    65 KT
 36HR VT     22/0000Z 22.9N  58.4W    70 KT
 48HR VT     22/1200Z 25.0N  59.0W    75 KT
 72HR VT     23/1200Z 30.5N  59.5W    65 KT
 96HR VT     24/1200Z 35.5N  56.0W    60 KT
120HR VT     25/1200Z 40.0N  48.0W    55 KT


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