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#462675 (Received by flhurricane at: 4:38 PM 28.Sep.2011) TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST WED SEP 28 2011 THE APPEARANCE OF PHILIPPE ON GEOSTATIONARY SATELLITE IMAGERY IS UNCHANGED SINCE THIS MORNING. CONVECTION IS LIMITED TO THE NORTHERN SEMICIRCLE OF THE STORM...AND THE LOW-LEVEL CENTER HAS BEEN PERIODICALLY EXPOSED DURING THE AFTERNOON. THE INITIAL INTENSITY REMAINS 35 KT BASED ON A BLEND OF DVORAK ESTIMATES FROM TAFB AND SAB. PHILIPPE CONTINUES TO MOVE TOWARD THE WEST-NORTHWEST AT ABOUT 10 KT. THE GLOBAL MODELS ALL SUGGEST THAT A WEAKNESS IN THE SUBTROPICAL RIDGE...INDUCED BY A LARGE MID-LATITUDE TROUGH OVER THE NORTHERN ATLANTIC...WILL ALLOW PHILIPPE TO MOVE NORTHWESTWARD OVER THE NEXT TWO DAYS. AFTER THAT...THE RIDGE IS FORECAST TO REBUILD...RESULTING IN A TURN BACK TOWARD THE WEST. MOST OF THE MODEL GUIDANCE NOW SUGGESTS A SLIGHTLY STRONGER RIDGE...RESULTING IN AN MORE WESTWARD MOTION AND AN INCREASED FORWARD SPEED OF THE CYCLONE. THEREFORE... THE OFFICIAL FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION TOWARD THE NEW MULTI-MODEL CONSENSUS. AN UPPER-LEVEL TROUGH CONTINUES TO PRODUCE STRONG VERTICAL SHEAR OVER PHILIPPE....WHICH IS EXPECTED TO CONTINUE FOR THE NEXT 12 TO 24 HOURS. THE SHIPS MODEL NOW SUGGESTS THAT THE SHEAR COULD BRIEFLY DECREASE BETWEEN 24 AND 48 HOURS...WHICH SHOULD ALLOW PHILIPPE TO MAINTAIN ITS INTENSITY FOR THE NEXT 2 OR 3 DAYS. GIVEN THIS...THE THE OFFICIAL FORECAST NOW MAINTAINS PHILIPPE AS A MINIMAL TROPICAL STORM FOR 72 HOURS. AFTER THAT...THE SHEAR IS EXPECTED TO INCREASE SUBSTANTIALLY...AND PHILIPPE IS FORECAST TO WEAKEN TO A REMNANT LOW BY THE END OF THE PERIOD. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 17.0N 39.7W 35 KT 40 MPH 12H 29/0600Z 17.9N 41.0W 35 KT 40 MPH 24H 29/1800Z 19.3N 42.7W 35 KT 40 MPH 36H 30/0600Z 20.9N 44.3W 35 KT 40 MPH 48H 30/1800Z 22.1N 46.1W 35 KT 40 MPH 72H 01/1800Z 23.6N 49.3W 35 KT 40 MPH 96H 02/1800Z 25.0N 53.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/1800Z 25.0N 56.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ FORECASTER BRENNAN/ZELINSKY |