000 WTNT42 KNHC 262039 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST MON SEP 26 2011 THE CLOUD PATTERN HAS REMAINED ABOUT THE SAME SINCE THIS MORNING WITH MOST OF THE DEEP CONVECTION OCCURRING OVER THE SOUTHERN PORTION OF THE CIRCULATION AND WELL-DEFINED LOW CLOUD LINES OVER THE NORTHERN SEMICIRCLE. A BLEND OF DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB GIVES 50 KT AGAIN FOR THE INITIAL WIND SPEED ESTIMATE. UPPER-LEVEL OUTFLOW IS STILL BEING IMPEDED OVER THE NORTHWEST QUADRANT...AS PHILIPPE CONTINUES TO BE AFFECTED BY MODERATE WESTERLY SHEAR. THE STORM IS EXPECTED TO REMAIN OVER MARGINALLY WARM WATERS AND ASSUMING THE SHEAR DOES NOT INCREASE TOO MUCH...SOME SLIGHT STRENGTHENING IS POSSIBLE THROUGH TOMORROW. HOWEVER...SIGNIFICANT INTENSIFICATION SEEMS UNLIKELY AT THIS TIME. AS PHILIPPE MOVES FARTHER NORTH...WESTERLY WINDS ALOFT ARE EXPECTED TO INCREASE AND THIS SHOULD CAUSE SOME WEAKENING TO COMMENCE BY 36 TO 48 HOURS. THE OFFICIAL WIND SPEED FORECAST FOLLOWS THE RELIABLE LGEM GUIDANCE. THE FORWARD MOTION HAS SLOWED AND IS NOW NEAR 315/7. DURING THE NEXT FEW DAYS...THE TROPICAL CYCLONE IS EXPECTED TO MOVE AROUND THE SOUTHWESTERN AND WESTERN PERIPHERY OF A SUBTROPICAL ANTICYCLONE OVER THE EXTREME EASTERN ATLANTIC. BY DAYS 3 TO 5...HOWEVER...THE TRACK GUIDANCE SPLITS INTO 2 GENERAL CAMPS. SOME MODELS SUCH AS THE HWRF...GFDL...GFDN...AND NOGAPS TURN PHILIPPE SHARPLY NORTHEASTWARD TO THE SOUTH OF A TROUGH OVER THE EASTERN ATLANTIC. OTHER MODELS SUCH AS THE GFS...ECMWF...AND UKMET HAVE THE CYCLONE MISSING THE TROUGH AND BECOMING TRAPPED UNDER A SUBTROPICAL RIDGE...RESULTING IN A GENERALLY WEST-NORTHWESTWARD MOTION. GIVEN THE WIDE RANGE OF POSSIBILITIES LATE IN THE FORECAST PERIOD...THE OFFICIAL FORECAST SHOWS ONLY A SLOW NORTHWARD MOTION FROM 72 TO 120 HOURS AS A COURSE OF LEAST REGRET. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 15.4N 34.4W 50 KT 60 MPH 12H 27/0600Z 16.1N 35.2W 55 KT 65 MPH 24H 27/1800Z 17.1N 36.2W 55 KT 65 MPH 36H 28/0600Z 18.2N 37.2W 50 KT 60 MPH 48H 28/1800Z 19.4N 38.3W 50 KT 60 MPH 72H 29/1800Z 22.0N 40.0W 45 KT 50 MPH 96H 30/1800Z 23.5N 40.0W 40 KT 45 MPH 120H 01/1800Z 24.5N 40.0W 35 KT 40 MPH $$ FORECASTER PASCH