000 WTNT42 KNHC 012033 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 31 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST SAT OCT 01 2011 AN ASCAT SWATH PARTIALLY CAUGHT PHILIPPE AT 1331 UTC...AND SOMEWHAT SURPRISINGLY...IT SHOWED A COUPLE OF 55-KT WIND BARBS LOCATED TO THE NORTH OF THE CENTER. THIS IS BEING SET AS THE INITIAL INTENSITY...AND IT COULD BE CONSERVATIVE DUE TO A POTENTIAL LOW BIAS IN THE DATA...AND BECAUSE THE ENTIRE WIND FIELD WAS NOT MEASURED BY THE INSTRUMENT. GIVEN THE HIGHER INITIAL INTENSITY... THE NEW OFFICIAL FORECAST HAS BEEN INCREASED THROUGHOUT THE FORECAST PERIOD BUT INDICATES THE SAME GENERAL PATTERN OF WEAKENING AND RE-STRENGTHENING AS BEFORE. THE REASONING FOR THIS INTENSITY FORECAST HAS NOT CHANGED. STRONG NORTHERLY SHEAR IS EXPECTED TO IMPACT PHILIPPE FOR THE NEXT 3 DAYS OR SO AND SHOULD INDUCE SOME GRADUAL WEAKENING. THE SHEAR COULD RELAX BY DAY 4 WHEN PHILIPPE REACHES A NARROW UPPER-LEVEL RIDGE AXIS...AND THE STATISTICAL MODELS...AS WELL AS THE GFDL...ARE SUGGESTING THAT SOME STRENGTHENING COULD OCCUR. THE INITIAL MOTION REMAINS 300 DEGREES AT 8 KT. A LOW- TO MID-LEVEL AREA OF HIGH PRESSURE OVER THE SUBTROPICAL CENTRAL ATLANTIC IS FORECAST TO BUILD SOUTHWESTWARD IN THE WAKE OF HURRICANE OPHELIA... AND THAT SHOULD TURN PHILIPPE WESTWARD OVER THE NEXT 24 TO 48 HOURS. THE GLOBAL MODELS AGREE THAT A WEAKNESS WILL DEVELOP IN THE RIDGE BY DAY 3 WITH PHILIPPE RESPONDING BY SLOWING DOWN AND TURNING TOWARD THE NORTH. THERE CONTINUES TO BE DISAGREEMENT AMONG THE MODELS ABOUT WHETHER OR NOT PHILIPPE WILL BE PICKED UP BY THE FLOW AHEAD OF A LARGE CUT-OFF LOW NEAR THE NEW ENGLAND COAST. THE GFS IS STILL A SLOWER AND SOUTHERN OUTLIER...HAVING PHILIPPE MISS THE TROUGH AND GETTING STUCK TO THE SOUTH OF A POST-FRONTAL HIGH PRESSURE SYSTEM. DUE TO THE LARGE SPREAD IN THE GUIDANCE...THE OFFICIAL FORECAST IS STILL SLOWER THAN THE MODEL CONSENSUS ON DAYS 4 AND 5. BASED ON THE ASCAT DATA...ADJUSTMENTS TO THE WIND RADII AND THE 12-FT SEAS RADII WERE REQUIRED ON THIS FORECAST ADVISORY. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 25.2N 49.1W 55 KT 65 MPH 12H 02/0600Z 25.6N 50.6W 55 KT 65 MPH 24H 02/1800Z 25.9N 52.6W 50 KT 60 MPH 36H 03/0600Z 25.8N 54.9W 45 KT 50 MPH 48H 03/1800Z 25.7N 57.1W 40 KT 45 MPH 72H 04/1800Z 26.5N 61.0W 40 KT 45 MPH 96H 05/1800Z 28.5N 61.0W 45 KT 50 MPH 120H 06/1800Z 32.0N 57.0W 50 KT 60 MPH $$ FORECASTER BERG