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#462355 (Received by flhurricane at: 4:38 PM 27.Sep.2011) TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST TUE SEP 27 2011 WESTERLY WIND SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH HAS DISPLACED THE DEEP CONVECTION MORE THAN 100 NM TO THE EAST OF THE LOW-LEVEL CENTER. GIVEN THE DECREASE IN ORGANIZATION OF THE CYCLONE...THE INITIAL INTENSITY IS LOWERED TO 35 KT IN AGREEMENT WITH THE FINAL-T NUMBERS FROM TAFB AND SAB. OUTPUT FROM THE SHIPS MODEL SUGGESTS THAT THE SHEAR WILL BE RATHER RELENTLESS OVER PHILIPPE DURING THE FORECAST PERIOD...ONLY DROPPING BELOW 15 KT BRIEFLY IN A COUPLE OF DAYS. THE SHEAR COMBINED WITH MARGINAL SSTS SHOULD RESULT IN SLOW WEAKENING OF PHILIPPE DURING THE NEXT DAY OR SO...AND LITTLE CHANGE THEREAFTER. THE NEW NHC FORECAST IS CLOSE TO THE LGEM MODEL THROUGH THE PERIOD...AND WELL BELOW THE DYNAMICAL HURRICANE MODELS WHICH CONTINUE TO INSIST ON STRENGTHENING THE CYCLONE DESPITE THE HOSTILE ENVIRONMENT. IT IS POSSIBLE THAT PHILIPPE COULD BECOME A POST-TROPICAL REMNANT LOW DURING THE PERIOD IF THE CONVECTION BECOMES DISPLACED EVEN FARTHER FROM THE CENTER. THE INITIAL MOTION IS NOW TOWARD THE WEST-NORTHWEST...OR 285/6... TAKING PHILIPPE A LITTLE TO THE LEFT OF THE PREVIOUS NHC TRACK. PHILIPPE CONTINUES TO BE STEERED BY A NARROW MID-LEVEL RIDGE TO THE NORTH...AND SHOULD CONTINUE MOVING AROUND THE PERIPHERY OF THIS FEATURE DURING THE PERIOD. THIS SHOULD RESULT IN A GENERAL WEST- NORTHWEST OR NORTHWEST MOTION OVER THE NEXT COUPLE OF DAYS...WITH A BEND BACK TO THE LEFT AND FASTER FORWARD SPEED AT THE END OF THE PERIOD AS THE RIDGE AMPLIFIES NORTH OF PHILIPPE. THE GUIDANCE FOR HAS SHIFTED QUITE A BIT TO THE LEFT AND IS ALSO FASTER FOR THIS CYCLE. THE NEW NHC TRACK FORECAST IS SIGNIFICANTLY TO THE LEFT OF AND FASTER THAN THE PREVIOUS ONE DUE TO THE INITIAL MOTION AND THE TREND IN THE GUIDANCE. EVEN WITH THIS ADJUSTMENT TO THE LEFT...THE NEW NHC TRACK STILL LIES TO THE RIGHT OF MOST OF THE RELIABLE MODELS AND THE NEW MULTI-MODEL CONSENSUS. IF PHILIPPE IS BECOMING A SHALLOWER CYCLONE...A TRACK EVEN MORE TOWARD THE WEST THAN SHOWN HERE IS POSSIBLE...SIMILAR TO THAT OF THE ECMWF. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 16.0N 36.0W 35 KT 40 MPH 12H 28/0600Z 16.4N 37.0W 35 KT 40 MPH 24H 28/1800Z 17.5N 38.5W 35 KT 40 MPH 36H 29/0600Z 18.9N 39.9W 30 KT 35 MPH 48H 29/1800Z 20.3N 41.0W 30 KT 35 MPH 72H 30/1800Z 22.6N 42.7W 30 KT 35 MPH 96H 01/1800Z 24.0N 44.5W 30 KT 35 MPH 120H 02/1800Z 25.5N 47.5W 30 KT 35 MPH $$ FORECASTER BRENNAN |