000 WTNT42 KNHC 280257 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 1100 PM AST TUE SEP 27 2011 SOUTHWESTERLY SHEAR CONTINUES TO TAKE ITS TOLL ON PHILIPPE. DEEP CONVECTION HAS BECOME QUITE LIMITED AND WHAT CONVECTION REMAINS IS LOCATED WELL TO THE NORTHEAST OF THE CENTER. HOWEVER...PHILIPPE IS CONSERVATIVELY KEPT AS A TROPICAL STORM...BASED ON A RECENT DVORAK CURRENT INTENSITY ESTIMATE OF 35 KT FROM TAFB. THE SHEAR IS EXPECTED TO REMAIN STRONG THROUGHOUT THE FORECAST PERIOD...EXCEPT FOR A SMALL WINDOW BETWEEN ABOUT 36 AND 60 HOURS. THE SHEAR ALONG WITH MARGINAL SEA SURFACE TEMPERATURES AND SOME DRIER AIR TO THE NORTHWEST OF THE CYCLONE IS LIKELY TO RESULT IN PHILIPPE BECOMING A TROPICAL DEPRESSION. THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE SHIPS/LGEM MODELS...AND MUCH BELOW THE DYNAMICAL GUIDANCE THAT DEEPENS THE CYCLONE IN A FEW DAYS. THE UPDATED FORECAST ALSO NOW SHOWS PHILIPPE BECOMING A POST-TROPICAL REMNANT LOW IN 4-5 DAYS...WHEN THE SHEAR INCREASE FURTHER. IF DEEP CONVECTION DOES NOT REDEVELOP NEAR THE CENTER OVERNIGHT OR ON WEDNESDAY...THE CYCLONE COULD BECOME A REMNANT LOW MUCH SOONER. THE INITIAL MOTION ESTIMATE IS 285/8. PHILIPPE IS FORECAST TO MOVE WEST-NORTHWESTWARD TO NORTHWESTWARD AROUND THE WESTERN PERIPHERY OF A MID-LEVEL RIDGE TO ITS NORTHEAST. AFTER 72 HOURS...A STRONG MID- TO UPPER-LEVEL RIDGE IS FORECAST TO BUILD OVER THE NORTH-CENTRAL ATLANTIC. THIS RIDGE IS EXPECTED TO TURN PHILIPPE...OR ITS REMNANTS...MORE TOWARD THE WEST LATER IN THE FORECAST PERIOD. THE GUIDANCE HAS AGAIN SHIFTED WESTWARD AND THE NEW NHC TRACK HAS BEEN ADJUSTED IN THAT DIRECTION. THE NHC FORECAST LIES BETWEEN THE GFS AND ECMWF MODELS AND IS IN BEST AGREEMENT WITH THE GFS ENSEMBLE MEAN AND THE EXPERIMENTAL HFIP MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 16.1N 37.0W 35 KT 40 MPH 12H 28/1200Z 16.5N 38.1W 30 KT 35 MPH 24H 29/0000Z 17.7N 39.7W 30 KT 35 MPH 36H 29/1200Z 19.1N 41.0W 30 KT 35 MPH 48H 30/0000Z 20.6N 42.1W 30 KT 35 MPH 72H 01/0000Z 22.8N 44.6W 30 KT 35 MPH 96H 02/0000Z 24.5N 47.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/0000Z 25.5N 50.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ FORECASTER BROWN