[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 290845
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 AM AST THU SEP 29 2011

THERE HAS BEEN LITTLE CHANGE IN THE SATELLITE APPEARANCE OF PHILIPPE
SINCE THE LAST ADVISORY.  THE CLOUD PATTERN CONSISTS OF A LARGE
BALL OF COLD-TOPPED CONVECTION...WITH THE LOW-LEVEL CENTER
ESTIMATED TO BE TO THE SOUTH OF THIS CONVECTIVE MASS.  SINCE THE
OVERALL STRUCTURE OF THE SYSTEM DOES NOT APPEAR TO HAVE CHANGED
SIGNIFICANTLY...THE CURRENT INTENSITY IS HELD AT 40 KT.  UW-CIMSS
AND SHIPS ANALYSES CONTINUE TO DIAGNOSE CLOSE TO 20 KT OF
SOUTHWESTERLY SHEAR OVER THE CYCLONE...ASSOCIATED WITH AN
UPPER-TROPOSPHERIC COLD LOW NEAR 17N46W.  GLOBAL MODELS FORECAST A
BRIEF PERIOD OF REDUCED SHEAR OVER PHILIPPE WITHIN THE NEXT 24-36
HOURS AS THE UPPER LOW SHIFTS WESTWARD.  THIS SUGGESTS THAT SOME
INTENSIFICATION COULD TAKE PLACE IN THE EARLY PART OF THE FORECAST
PERIOD.  THEREAFTER...PHILIPPE IS LIKELY TO WEAKEN AS IT BECOMES
AFFECTED BY EXTREMELY STRONG NORTH-NORTHWESTERLY SHEAR ASSOCIATED
WITH THE UPPER-LEVEL OUTFLOW OF TROPICAL CYCLONE OPHELIA.  THIS
ENVIRONMENT SHOULD RESULT IN THE SYSTEM DEGENERATING INTO A REMNANT
LOW BY DAY 4.

SINCE IT IS NOT CLEAR JUST HOW FAR TO THE SOUTH OF THE DEEP
CONVECTION THE CENTER IS LOCATED...THE INITIAL MOTION IS A RATHER
UNCERTAIN 300/11.  PHILIPPE IS LIKELY TO CONTINUE TO MOVE
WEST-NORTHWESTWARD ON THE SOUTHWESTERN SIDE OF A SUBTROPICAL HIGH
OVER THE EASTERN ATLANTIC FOR THE NEXT DAY OR TWO.  LATER IN THE
FORECAST PERIOD...A BUILDING SUBTROPICAL HIGH OVER THE CENTRAL
ATLANTIC SHOULD CAUSE PHILIPPE TO TURN TOWARD THE WEST.  THE
OFFICIAL FORECAST TRACK IS ADJUSTED A LITTLE FARTHER SOUTH FROM THE
PREVIOUS ONE AND IS ABOUT IN THE MIDDLE OF THE GUIDANCE ENVELOPE.

FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 17.8N  41.7W   40 KT  45 MPH
 12H  29/1800Z 18.6N  43.2W   45 KT  50 MPH
 24H  30/0600Z 19.9N  45.0W   50 KT  60 MPH
 36H  30/1800Z 21.3N  46.8W   50 KT  60 MPH
 48H  01/0600Z 22.3N  48.8W   45 KT  50 MPH
 72H  02/0600Z 23.9N  52.7W   35 KT  40 MPH
 96H  03/0600Z 24.5N  56.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  04/0600Z 24.5N  60.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER PASCH/KIMBERLAIN


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