[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 010851
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  29
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
500 AM AST SAT OCT 01 2011

ALTHOUGH PHILIPPE APPEARS TO BE IN AN UNFAVORABLE ATMOSPHERIC
ENVIRONMENT...THE STORM IS NOT WEAKENING. IN FACT...DEEP CONVECTION
HAS BEEN INCREASING DURING THE LAST SEVERAL HOURS WITH CLOUD TOPS
NOW AS COLD AS -85C. A 0501 UTC AMSR-E OVERPASS INDICATED THAT THE
LOW-LEVEL CENTER WAS LOCATED NEAR THE WESTERN EDGE OF THE
CONVECTION...AND THAT THE VORTEX WAS TILTED TO THE SOUTHEAST WITH
HEIGHT. DVORAK CLASSIFICATIONS ARE 45 KT FROM BOTH TAFB AND
SAB...SO THE INITIAL WIND SPEED IS HELD AT THAT VALUE. HOWEVER...
RECENT ADT ESTIMATES FROM UW-CIMSS SUGGEST THAT PHILIPPE COULD BE A
LITTLE STRONGER.

THE TROPICAL STORM IS STILL MOVING NORTHWESTWARD AT ABOUT 8 KT.
PHILIPPE IS FORECAST TO GRADUALLY TURN TOWARD THE WEST DURING THE
NEXT FEW DAYS AS IT MOVES TO THE SOUTH OF A STRONG SUBTROPICAL
RIDGE. BEYOND THAT TIME...THE CYCLONE IS EXPECTED TO TURN TOWARD
THE NORTH AND THEN NORTH-NORTHEAST AS A DEEP-LAYER TROUGH...THE
SAME ONE THAT IS INFLUENCING THE TRACK OF OPHELIA...ERODES THE
RIDGE. THE NEW TRACK FORECAST SHOWS A SHARPER TURN AT THE END OF
THE PERIOD...IN AGREEMENT WITH MOST OF THE GUIDANCE...AND IS ABOUT
MIDWAY BETWEEN THE PREVIOUS FORECAST AND THE ECMWF MODEL.

NORTHWESTERLY SHEAR OF ABOUT 30 KT...ASSOCIATED WITH THE OUTFLOW OF
OPHELIA...IS CURRENTLY IMPACTING PHILIPPE. THE SHIPS MODEL SHOWS
THE SHEAR VECTOR TURNING TOWARD THE NORTH AND INCREASING TO NEAR 40
KT DURING THE NEXT 36 HOURS. THIS HIGHLY UNFAVORABLE ENVIRONMENT
SHOULD CAUSE AT LEAST SOME WEAKENING. IF PHILIPPE IS ABLE TO
SURVIVE DURING THE NEXT TWO TO THREE DAYS...IT MAY HAVE A CHANCE TO
RESTRENGTHEN A LITTLE AS IT MOVES INTO AN ENVIRONMENT OF LOWER
SHEAR. BY DAY 5...HOWEVER...A BURST OF SOUTHWESTERLY SHEAR
ASSOCIATED WITH THE AFOREMENTIONED TROUGH IS EXPECTED. THE NHC
INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS ONE AND LIES AT THE
LOW END OF THE GUIDANCE NEAR THE LGEM.

FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 24.3N  47.4W   45 KT  50 MPH
 12H  01/1800Z 25.0N  48.6W   45 KT  50 MPH
 24H  02/0600Z 25.7N  50.4W   40 KT  45 MPH
 36H  02/1800Z 26.2N  52.3W   35 KT  40 MPH
 48H  03/0600Z 26.4N  54.4W   30 KT  35 MPH
 72H  04/0600Z 26.6N  58.5W   30 KT  35 MPH
 96H  05/0600Z 28.5N  60.5W   35 KT  40 MPH
120H  06/0600Z 32.0N  59.0W   35 KT  40 MPH

$$
FORECASTER CANGIALOSI



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