[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 021444
TCDAT2

TROPICAL STORM PHILIPPE DISCUSSION NUMBER  34
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172011
1100 AM AST SUN OCT 02 2011

PHILIPPE HAS BECOME AN EXPOSED SWIRL OF LOW CLOUDS ACCOMPANIED BY A
SHRINKING AREA OF DEEP CONVECTION TO THE SOUTHEAST...AND IT ONLY
TOOK 30-40 KT OF SHEAR TO MAKE THAT HAPPEN.  DVORAK CURRENT
INTENSITY NUMBERS ARE 3.0...OR 45 KT...FROM TAFB AND SAB.  IN
ADDITION...VARIOUS SATELLITE PRODUCTS FROM THE CIMSS GROUP AT THE
UNIVERSITY OF WISCONSIN ARE PROVIDING ESTIMATES BETWEEN 40 AND 45
KT.  THE INITIAL INTENSITY IS THEREFORE LOWERED TO 45 KT ON THIS
ADVISORY.

AS THE DEEP CONVECTION BECAME SHEARED OFF TO THE SOUTHEAST EARLIER
THIS MORNING...THE LOW-LEVEL CENTER APPEARED TO MAKE A JOG TO THE
NORTHWEST.  THE 12-HOUR SMOOTHED MOTION IS 295 DEGREES AT 10 KT.
THE TRACK GUIDANCE CONTINUES TO AGREE ON A WESTWARD MOTION DURING
THE NEXT 48 HOURS AS PHILIPPE IS STEERED BY A SUBTROPICAL HIGH TO
ITS NORTH.  THE CYCLONE REACHES A WEAKNESS IN THE RIDGE CREATED BY
A MID- TO UPPER-LEVEL CUT-OFF LOW NEAR SOUTHEASTERN CANADA BY 72
HOURS...AND THIS SHOULD CAUSE IT TO TURN SLOWLY NORTH AND
NORTHEASTWARD ON DAYS 3 AND 4.  SOME ACCELERATION TO THE NORTHEAST
IS FORECAST ON DAY 5 AS PHILIPPE BECOMES EMBEDDED IN DEEP-LAYER
SOUTHWESTERLY FLOW.  FOR THE FIRST 48 HOURS...THE OFFICIAL FORECAST
IS NORTH OF THE MODEL CONSENSUS AND LEANS TOWARD THE BAM SHALLOW
MODEL...WHICH SEEMS TO HAVE HAD A MORE ACCURATE MOTION RECENTLY.
AFTER 72 HOURS...THE FORECAST SHOWS A WIDER AND FASTER RE-CURVATURE
THAN THE CONSENSUS MODELS...AND THIS SCENARIO IS SUPPORTED BY THE
ECMWF AND THE BAM SHALLOW AND MEDIUM MODELS.

THE INTENSITY FORECAST REMAINS OF LOW CONFIDENCE.  THE SHIPS
GUIDANCE SUGGESTS THAT THE NORTHERLY VERTICAL SHEAR OVER PHILIPPE
HAS PEAKED AND SHOULD GRADUALLY RELAX OVER THE NEXT 72 HOURS.  SOME
WEAKENING IS INDICATED IN THE OFFICIAL FORECAST DURING THAT PERIOD.
TAKING IT A STEP FURTHER...THE ECMWF HAS BEEN FAIRLY CONSISTENT IN
SHOWING PHILIPPE DISSIPATING AHEAD OF A FRONTAL BOUNDARY BY DAY 3.
ALTHOUGH THAT IS A PLAUSIBLE SCENARIO...THE OFFICIAL FORECAST
CONTINUES TO FOLLOW THE MAIN INTENSITY MODELS FOR NOW AND SHOWS THE
POSSIBILITY OF SOME RE-STRENGTHENING ON DAYS 3 THROUGH 5.
HOWEVER...IT IS NOT AS AGGRESSIVE AS THE GFDL...HWRF...AND FSU
SUPERENSEMBLE...ALL OF WHICH INDICATE THAT PHILIPPE WILL BECOME A
SIGNIFICANT HURRICANE.

FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 26.3N  51.7W   45 KT  50 MPH
 12H  03/0000Z 26.5N  53.4W   40 KT  45 MPH
 24H  03/1200Z 26.3N  55.5W   35 KT  40 MPH
 36H  04/0000Z 26.2N  57.7W   35 KT  40 MPH
 48H  04/1200Z 26.3N  59.8W   35 KT  40 MPH
 72H  05/1200Z 28.0N  62.0W   40 KT  45 MPH
 96H  06/1200Z 30.0N  60.5W   50 KT  60 MPH
120H  07/1200Z 32.5N  56.0W   50 KT  60 MPH

$$
FORECASTER BERG


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