[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 011445
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  30
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
1100 AM AST SAT OCT 01 2011

PHILIPPE IS LOOKING MORE AND MORE LIKE A SHEARED TROPICAL CYCLONE
DUE TO STRONG NORTHWESTERLY UPPER-LEVEL WINDS.  DEEP CONVECTION IS
PRIMARILY LIMITED NEAR AND TO THE EAST OF THE CENTER...BUT THE
INITIAL INTENSITY WILL REMAIN 45 KT BASED ON SIMILAR DVORAK
ESTIMATES FROM TAFB...SAB...AND THE UW-CIMSS ADT.

PHILIPPE IS LOCATED TO THE SOUTH OF A LOW- TO MID-LEVEL ANTICYCLONE
AND HAS TURNED WEST-NORTHWESTWARD WITH A MOTION OF 300 DEGREES AT 8
KT.  GLOBAL MODEL FIELDS ARE INDICATING THAT A RIDGE AXIS WILL
BUILD SOUTHWESTWARD AS HURRICANE OPHELIA MOVES OUT OF THE AREA...AND
THIS FEATURE SHOULD FORCE PHILIPPE ON A GENERAL WESTWARD MOTION
BETWEEN 24 AND 72 HOURS.  THE STORM IS THEN EXPECTED TO REACH A
WEAKNESS IN THE RIDGE CREATED BY A MID- TO UPPER-LEVEL CUT-OFF LOW
OVER THE WESTERN ATLANTIC...AND CONSEQUENTLY MAKE A SLOW TURN
TOWARD THE NORTH AND NORTHEAST ON DAYS 4 AND 5.  ALL OF THE TRACK
MODELS AGREE ON THIS SCENARIO...BUT THE GFS SHOWS A SMALLER CUT-OFF
LOW AND LEAVES PHILIPPE IN A WEAKER STEERING FLOW.  THIS MAKES THE
GFS A SLOWER...SOUTHERN OUTLIER RELATIVE TO THE OTHER MODELS.  OUT
OF RESPECT FOR THAT MODEL...THE OFFICIAL FORECAST IS A LITTLE
SLOWER THAN THE TVCA CONSENSUS AND THE PREVIOUS FORECAST ON DAYS 4
AND 5.

THIRTY TO FORTY KNOTS OF NORTHERLY VERTICAL SHEAR IS FORECAST TO
AFFECT PHILIPPE DURING THE NEXT COUPLE OF DAYS...BUT IT IS BECOMING
MORE APPARENT THAT THE CYCLONE MAY BE RESILIENT ENOUGH TO WITHSTAND
THIS ENVIRONMENT.  PHILIPPE WILL BY NO MEANS BE A HEALTHY-LOOKING
CYCLONE...BUT IT SHOULD NOT BE TOO DIFFICULT FOR IT TO MAINTAIN
CONVECTION AND REMAIN AS A TROPICAL CYCLONE WHILE IT MOVES OVER
WARMER WATERS.  THE OFFICIAL FORECAST IS CLOSE TO THE INTENSITY
CONSENSUS AND INDICATES WEAKENING DURING THE FIRST 72 HOURS.  SOME
RE-STRENGTHENING IS INDICATED ON DAYS 4 AND 5 WHEN PHILIPPE ENTERS
A LOWER-SHEAR ENVIRONMENT...BUT THE OFFICIAL FORECAST...WHICH IS OF
LOW CONFIDENCE...IS NOT AS HIGH AS THE INTENSITY MODELS DURING THAT
PERIOD.

FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 24.8N  48.0W   45 KT  50 MPH
 12H  02/0000Z 25.4N  49.4W   45 KT  50 MPH
 24H  02/1200Z 25.9N  51.3W   40 KT  45 MPH
 36H  03/0000Z 26.1N  53.2W   35 KT  40 MPH
 48H  03/1200Z 25.9N  55.3W   35 KT  40 MPH
 72H  04/1200Z 26.0N  59.5W   30 KT  35 MPH
 96H  05/1200Z 28.0N  61.0W   35 KT  40 MPH
120H  06/1200Z 30.5N  58.5W   40 KT  45 MPH

$$
FORECASTER BERG

WWWW
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