000 WTNT42 KNHC 030852 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 37 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 AM AST MON OCT 03 2011 THE STRUCTURE OF PHILIPPE HAS CHANGED LITTLE DURING THE LAST SEVERAL HOURS. MICROWAVE DATA INDICATE THAT THE LOW-LEVEL CENTER IS LOCATED NEAR THE NORTHWESTERN EDGE OF THE CONVECTIVE MASS...WHICH HAS EXPANDED SLIGHTLY DURING THE PAST FEW HOURS. AN ASCAT OVERPASS JUST AFTER 0000 UTC INDICATED THAT MAXIMUM WINDS WERE AROUND 45 KT. THE LATEST DVORAK CI NUMBERS FROM TAFB AND SAB ARE ALSO 45 KT... THEREFORE...THE INITIAL WIND SPEED IS HELD AT THAT VALUE. THE SHIPS MODEL INDICATES THAT ABOUT 30 KT OF NORTHERLY SHEAR IS CURRENTLY AFFECTING PHILIPPE. HOWEVER...AS MENTIONED IN THE PREVIOUS DISCUSSION...THERE IS SOME INDICATION THAT THE SHEAR IS PRIMARILY IN THE HIGHER LEVELS OF THE ATMOSPHERE RATHER THAN EXTENDING THROUGHOUT THE DEPTH OF THE TROPOSPHERE. THIS COULD BE THE REASON WHY PHILIPPE HAS NOT WEAKENED SIGNIFICANTLY DURING THE PAST FEW DAYS DESPITE BEING IN ANALYZED SHEAR OF 30 KT OR HIGHER. NONETHELESS...THE SHEAR IS EXPECTED TO LESSEN IN THE 36-72 HOUR TIME FRAME...AND THAT COULD ALLOW THE TROPICAL STORM TO STRENGTHEN. BEYOND A FEW DAYS...SOUTHWESTERLY SHEAR IS ANTICIPATED TO INCREASE SIGNIFICANTLY AND SHOULD INDUCE WEAKENING. THE OFFICIAL FORECAST IS ONCE AGAIN NEAR THE INTENSITY MODEL CONSENSUS AND IS A LITTLE HIGHER THAN THE PREVIOUS ONE. PHILIPPE APPEARS TO NOW BE MOVING A LITTLE SOUTH OF DUE WEST...AND THE LATEST INITIAL MOTION ESTIMATE IS 265/10. THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 TO 36 HOURS AS THE STORM REMAINS TO THE SOUTH OF A MID-LEVEL RIDGE. THEREAFTER...THE RIDGE IS EXPECTED TO WEAKEN IN RESPONSE TO A LARGE TROUGH MOVING INTO THE WESTERN ATLANTIC. THIS SHOULD CAUSE PHILIPPE TO GRADUALLY TURN NORTHWARD IN 48 TO 72 HOURS...AND THEN NORTHEASTWARD IN THE THREE TO FIVE DAY TIME PERIOD. ALTHOUGH THE MODELS ARE IN GOOD AGREEMENT ON THE EVOLUTION OF THE LARGE-SCALE FLOW PATTERN...THERE REMAINS CONSIDERABLE SPREAD IN THE TRACK GUIDANCE FOR PHILIPPE. THIS SPREAD IS IN PART DUE TO THE DIFFERENCES IN THE STRENGTH OF PHILIPPE IN THE MODELS. IN GENERAL...THE GUIDANCE HAS TRENDED A LITTLE FASTER AT THE END OF THE FORECAST PERIOD AND THE OFFICIAL TRACK FORECAST HAS FOLLOWED SUIT. THE 34-KT WIND RADII HAVE BEEN ADJUSTED BASED ON THE AFOREMENTIONED ASCAT PASS. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 25.8N 54.9W 45 KT 50 MPH 12H 03/1800Z 25.6N 56.6W 45 KT 50 MPH 24H 04/0600Z 25.5N 58.9W 40 KT 45 MPH 36H 04/1800Z 25.8N 60.7W 40 KT 45 MPH 48H 05/0600Z 26.5N 61.3W 45 KT 50 MPH 72H 06/0600Z 28.3N 60.1W 55 KT 65 MPH 96H 07/0600Z 30.5N 57.0W 45 KT 50 MPH 120H 08/0600Z 33.0N 52.5W 40 KT 45 MPH $$ FORECASTER CANGIALOSI