Show Selection: |
#462004 (Received by flhurricane at: 4:50 AM 26.Sep.2011) TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 AM AST MON SEP 26 2011 THE CENTRAL DEEP CONVECTION ASSOCIATED WITH PHILIPPE HAS BEEN INCREASING IN INTENSITY AND COVERAGE DURING THE PAST SEVERAL HOURS...WITH CLOUD TOPS AS COLD AS -90C. HOWEVER...THE CURVED BAND THAT HAS BEEN PRESENT OVER THE WESTERN SEMICIRCLE IS NOW LESS DISTINCT. THE INITIAL WIND SPEED IS HELD AT 50 KT...WHICH IS THE AVERAGE OF THE SATELLITE INTENSITY ESTIMATES FROM TAFB...SAB...AND UW-CIMSS. NIGHT CHANNEL VISIBLE IMAGERY AND A 0453 UTC TRMM OVERPASS SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED ON THE NORTHERN SIDE OF THE CONVECTION. THE INITIAL MOTION IS 300/11. PHILIPPE IS LOCATED ON THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL HIGH EXTENDING WESTWARD FROM WEST AFRICA. THE CYCLONE IS EXPECTED TO TURN NORTHWESTWARD AND SLOW DOWN DURING THE NEXT COUPLE OF DAYS AS IT BEGINS TO FEEL THE INFLUENCE OF A DEEP-LAYER TROUGH TO ITS NORTH...AND THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ON THAT SCENARIO. BEYOND TWO DAYS... HOWEVER...THE MODELS BECOME QUITE DIVERGENT. THE ECMWF MODEL HAS SHIFTED EVEN FARTHER WEST...SHOWING A FAIRLY STEADY WEST-NORTHWEST TO NORTHWEST MOTION. ON THE OTHER HAND...THE GFDL...NOGAPS...AND GFDN MODELS SHOW PHILIPPE TURNING NORTHEASTWARD BY THE END OF THE FORECAST PERIOD. THESE DIVERGENT SOLUTIONS APPEAR TO BE ASSOCIATED WITH THE AMPLITUDE OF THE LONGWAVE TROUGH TO THE NORTH OF PHILIPPE AND THE VERTICAL INTEGRITY OF THE TROPICAL CYCLONE. THE OFFICIAL FORECAST...WHICH WAS ADJUSTED SLIGHTLY TO THE WEST...LIES BETWEEN THE EXTREMES AND ENDS UP NEAR THE GFS AND HWRF MODELS. THE SHIPS MODEL SHOWS SOUTHWESTERLY SHEAR INCREASING TO 15-20 KT WITHIN THE NEXT 12 TO 24 HOURS AND PERSISTING THROUGH THE END OF THE FORECAST PERIOD. THIS LESS FAVORABLE ATMOSPHERIC ENVIRONMENT AND SLIGHTLY COOLER WATERS ALONG THE FORECAST TRACK ARE NOT FAVORABLE FOR STRENGTHENING. THEREFORE...THE OFFICIAL FORECAST IS A LITTLE LOWER THAN THE PREVIOUS ONE AND FOLLOWS THE TREND IN THE SHIPS/LGEM MODELS...WHICH SHOW A GRADUAL WEAKENING BEYOND 24-36 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 14.7N 33.4W 50 KT 60 MPH 12H 26/1800Z 15.5N 34.5W 55 KT 65 MPH 24H 27/0600Z 16.4N 35.4W 55 KT 65 MPH 36H 27/1800Z 17.3N 36.5W 55 KT 65 MPH 48H 28/0600Z 18.3N 37.8W 50 KT 60 MPH 72H 29/0600Z 20.8N 40.0W 50 KT 60 MPH 96H 30/0600Z 23.5N 40.5W 45 KT 50 MPH 120H 01/0600Z 25.5N 40.5W 45 KT 50 MPH $$ FORECASTER CANGIALOSI |