000 WTNT42 KNHC 252047 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST SUN SEP 25 2011 THE APPEARANCE OF PHILIPPE ON VISIBLE IMAGERY HAS IMPROVED OVER THE PAST FEW HOURS. CONVECTION HAS PERSISTED ALONG A CURVED BAND LOCATED TO THE WEST AND SOUTH OF THE MAIN CENTER OF CIRCULATION... AND A CDO-LIKE CENTRAL CONVECTIVE FEATURE HAS ALSO DEVELOPED. DVORAK ESTIMATES OF INTENSITY HAVE INCREASED SINCE THE LAST ADVISORY...AND A BLEND OF THESE ESTIMATES YIELDS AN INITIAL INTENSITY OF 50 KT. PHILIPPE IS MOVING TO THE NORTHWEST TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE. THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS...AND THERE IS GOOD AGREEMENT AMONG THE MODELS THROUGH 48 HOURS. BEYOND THAT TIME...THE UNCERTAINTY INCREASES AS SOME MODELS RECURVE THE TROPICAL CYCLONE TOWARDS THE NORTHEAST... WHILE OTHERS ALLOW THE RIDGE TO REBUILD...RESULTING IN A MORE WESTWARD TRACK. THIS DISCREPANCY IS LIKELY RELATED TO THE INTENSITY OF PHILIPPE...AS A DEEPER AND STRONGER SYSTEM WILL LIKELY MOVE FARTHER NORTH...WHILE A WEAKER SYSTEM WILL BE STEERED TO THE WEST BY LOWER LEVEL EASTERLIES. OVERALL...THE GUIDANCE ENVELOPE HAS SHIFTED WESTWARD...AND THE TRACK HAS BEEN NUDGED IN THAT DIRECTION ACCORDINGLY. THE ENVIRONMENT AROUND PHILIPPE CONTINUES TO BE CONDUCIVE FOR INTENSIFICATION. THIS FAVORABLE ENVIRONMENT IS EXPECTED TO PERSIST FOR THE NEXT 24 TO 36 HOURS. AFTER THAT...PHILIPPE WILL BEGIN INTERACTING WITH AN UPPER-LEVEL TROUGH...WHICH SHOULD RESULT IN A SUBSTANTIAL INCREASE IN THE VERTICAL WIND SHEAR. ADDITIONALLY... THE CYCLONE WILL BEGIN MOVING OVER COOLER SSTS AND INTO A MORE STABLE ENVIRONMENT. THE OFFICIAL INTENSITY FORECAST HAS NOT CHANGED SUBSTANTIALLY...AND THE FORECAST STILL CALLS FOR PHILIPPE TO APPROACH HURRICANE INTENSITY WITHIN THE NEXT COUPLE OF DAYS. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 13.2N 31.7W 50 KT 60 MPH 12H 26/0600Z 14.0N 33.1W 55 KT 65 MPH 24H 26/1800Z 15.1N 34.7W 60 KT 70 MPH 36H 27/0600Z 16.1N 35.9W 65 KT 75 MPH 48H 27/1800Z 17.3N 36.9W 60 KT 70 MPH 72H 28/1800Z 20.0N 38.7W 55 KT 65 MPH 96H 29/1800Z 22.5N 39.5W 55 KT 65 MPH 120H 30/1800Z 25.0N 39.5W 50 KT 60 MPH $$ FORECASTER ZELINSKY/STEWART