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#462515 (Received by flhurricane at: 5:02 AM 28.Sep.2011) TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 AM AST WED SEP 28 2011 DURING THE LAST SEVERAL HOURS DEEP CONVECTION HAS BEEN INCREASING IN INTENSITY AND COVERAGE TO THE NORTH AND NORTHEAST OF THE CENTER OF PHILIPPE. HOWEVER...THIS CONVECTION HAS BEEN UNABLE TO WRAP AROUND THE CIRCULATION DUE TO ABOUT 20 KT OF SOUTHWESTERLY SHEAR. THE INITIAL WIND SPEED IS HELD AT 35 KT FOR THIS ADVISORY...IN AGREEMENT WITH DVORAK CLASSIFICATIONS FROM TAFB AND ADT VALUES FROM UW-CIMSS. OTHER THAN A BRIEF DECREASE IN THE WIND SHEAR IN 36-48 HOURS...THE SHIPS MODEL MAINTAINS SHEAR VALUES OF 20 KT OR HIGHER OVER PHILIPPE DURING THE NEXT SEVERAL DAYS. ACCORDINGLY... THE SHIPS AND LGEM MODELS SHOW LITTLE CHANGE IN STRENGTH OR A SLIGHT WEAKENING THROUGHOUT THE FORECAST PERIOD. ON THE OTHER HAND...THE FSSE...GFDL...AND HWRF MODELS CONTINUE TO INTENSIFY THIS SYSTEM AND BRING PHILIPPE TO HURRICANE STRENGTH. THE LATTER SCENARIO APPEARS HIGHLY UNLIKELY...AND THE OFFICIAL FORECAST CLOSELY FOLLOWS THE SHIPS/LGEM GUIDANCE. PHILIPPE IS FORECAST TO BECOME A REMNANT LOW BY DAY 4 WHEN THE SHEAR IS EXPECTED TO BE IN EXCESS OF 30 KT. PHILIPPE IS MOVING WEST-NORTHWESTWARD AT ABOUT 10 KT TO THE SOUTH OF A NARROW MID-LEVEL RIDGE. THIS RIDGE IS EXPECTED TO WEAKEN DURING THE NEXT COUPLE OF DAYS DUE TO THE AMPLIFICATION OF A LARGE-SCALE TROUGH OVER THE NORTHEASTERN ATLANTIC...WHICH SHOULD CAUSE THE CYCLONE TO TURN NORTHWESTWARD DURING THAT TIME PERIOD. BEYOND THAT...PHILIPPE...OR ITS REMNANT LOW...IS EXPECTED TO TURN BACK TOWARD THE LEFT AS THE SUBTROPICAL RIDGE RESTRENGTHENS. THE MODEL GUIDANCE HAS SHIFTED A LITTLE MORE TO THE WEST THIS CYCLE...AND THE OFFICIAL FORECAST FOLLOWS THAT TREND BUT IS TO THE RIGHT OF THE MULTI-MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 16.5N 38.0W 35 KT 40 MPH 12H 28/1800Z 17.2N 39.1W 35 KT 40 MPH 24H 29/0600Z 18.4N 40.7W 30 KT 35 MPH 36H 29/1800Z 19.8N 42.0W 30 KT 35 MPH 48H 30/0600Z 21.2N 43.4W 30 KT 35 MPH 72H 01/0600Z 23.2N 45.9W 30 KT 35 MPH 96H 02/0600Z 24.5N 49.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/0600Z 25.5N 52.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ FORECASTER CANGIALOSI |