[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 200830
TCDAT2
HURRICANE PHILIPPE DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT TUE SEP 20 2005

PHILIPPE'S CLOUD PATTERN IS CHARACTERIZED BY A RATHER AMORPHOUS-
LOOKING MASS OF VERY DEEP CONVECTION...ALTHOUGH RECENT SATELLITE
IMAGES SUGGEST THAT IT MAY BE DEVELOPING SORT OF A COMMA SHAPE.
THE LACK OF UPPER-LEVEL OUTFLOW OVER THE WESTERN SECTORS OF THE
HURRICANE SUGGESTS SOME WESTERLY SHEARING...DUE TO THE FLOW AT THE
BASE OF A BROAD UPPER-TROPOSPHERIC TROUGH ASSOCIATED WITH THE
OUTFLOW TO THE EAST OF RITA.  ALTHOUGH THE SHIPS MODEL ALSO
DIAGNOSES SIGNIFICANT SHEAR AFFECTING PHILIPPE DURING THE FORECAST
PERIOD...IT NONETHELESS PREDICTS SOME STRENGTHENING.  THE OFFFICIAL
FORECAST SIMILARLY SHOWS AN INCREASE IN STRENGTH UP TO 48
HOURS...BUT GOES A FAIR AMOUNT BELOW SHIPS THEREAFTER BECAUSE THE
SHEAR IS EXPECTED TO BECOME SIMPLY TOO STRONG FOR PHILIPPE TO
MAINTAIN ITS INTENSITY BY THAT TIME.

I HAVE ESTIMATED THE CENTER TO BE WEST OF THE FIXES FROM THE VARIOUS
AGENCIES...BOTH FOR CONTINUITY FROM THE PREVIOUS TRACK...AND THE
PRESENCE OF WESTERLY SHEAR.  TRACK FORECAST PHILOSPHY REMAINS
ESSENTIALLY UNCHANGED FROM THE PAST FEW ADVISORY PACKAGES.
PHILIPPE IS MOVING TOWARD A BREAK IN THE SUBTROPICAL RIDGE IN THE
VICINITY OF 60W.  LATE IN THE FORECAST PERIOD...A STRONG 500 MB
SHORTWAVE TROUGH IS EXPECTED TO DIG SOUTHWARD FROM THE CANADIAN
MARITIMES.  THIS FEATURE SHOULD CAUSE PHILIPPE TO ACCELERATE
NORTHEASTWARD BY DAYS 4-5.  THE OFFICIAL TRACK FORECAST IS QUITE
SIMILAR TO THE PREVIOUS ONE...AND ALONG THE GENERAL TRAJECTORY
OF...BUT A LITTLE SLOWER THAN...THE DYNAMICAL MODEL CONSENSUS.

FORECASTER PASCH


FORECAST POSITIONS AND MAX WINDS

INITIAL      20/0900Z 18.8N  56.8W    70 KT
 12HR VT     20/1800Z 19.8N  57.2W    70 KT
 24HR VT     21/0600Z 21.3N  57.6W    75 KT
 36HR VT     21/1800Z 23.0N  58.1W    80 KT
 48HR VT     22/0600Z 25.0N  58.6W    85 KT
 72HR VT     23/0600Z 29.5N  59.5W    75 KT
 96HR VT     24/0600Z 34.0N  58.0W    65 KT
120HR VT     25/0600Z 38.0N  52.0W    60 KT


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