ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM PHILIPPE DISCUSSION NUMBER 45 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 AM AST WED OCT 05 2011 PHILIPPE CONTINUES TO HAVE A SHEARED PRESENTATION ON SATELLITE IMAGES...ALTHOUGH THERE IS SOME EVIDENCE OF A VERY RAGGED EYE OCCASIONALLY. DVORAK ESTIMATES ARE UNCHANGED FROM SIX HOURS AGO...SO THE INITIAL INTENSITY WILL REMAIN 55 KT. MOST OF THE GLOBAL MODELS SUGGEST THAT PHILIPPE WILL MOVE BENEATH AN UPPER- LEVEL RIDGE AXIS LATER TODAY...RESULTING IN A PERIOD OF LOWER SHEAR LASTING FOR A DAY OR SO. ALL OF THE MODELS SHOW SOME INTENSIFICATION DURING THAT PERIOD...AND THE OFFICIAL FORECAST FOLLOWS THAT SOLUTION...ALBEIT ON THE LOWER END OF THE GUIDANCE SPECTRUM BELOW THE MODEL CONSENSUS. AFTER THAT TIME... SOUTHWESTERLY SHEAR SHOULD SIGNIFICANTLY INCREASE DUE TO A LARGE TROUGH OVER THE WESTERN ATLANTIC. USUALLY A MORE SIGNIFICANT WEAKENING WOULD BE CALLED FOR WITH SUCH STRONG SHEAR...BUT ONLY A MINOR DECREASE IN STRENGTH IS FORECAST DUE TO SIGNIFICANT BAROCLINIC FORCING. EXTRATROPICAL TRANSITION IS EXPECTED BY DAY 4...AND IT IS WORTH NOTING THAT MOST OF THE GLOBAL GUIDANCE EVEN HAVE PHILIPPE EXTRATROPICAL NEAR DAY 3 IN THE LATEST RUNS...BUT I DID NOT WANT TO SHOW SUCH A LARGE CHANGE FROM THE PREVIOUS FORECAST. SOME COARSE AMSU DATA SUGGEST THAT THE TROPICAL CYCLONE IS MOVING AT 300/5...ABOUT THE SAME AS PREVIOUS. A RELATIVELY SHARP TURN TO THE NORTH AND NORTHEAST IS LIKELY WITHIN A DAY OR SO DUE TO THE AFOREMENTIONED TROUGH OVER THE WESTERN ATLANTIC. THIS TROUGH SHOULD ALSO CAUSE PHILIPPE TO MOVE AT AN INCREASING PACE BY LATE THURSDAY AS THE TROPICAL CYCLONE IS STEERED BY THE STRONGER MID-LATITUDE FLOW. THE NEW FORECAST IS CLOSE TO THE PREVIOUS ONE...BUT IS A BIT FASTER TO ACCOUNT FOR RECENT MODEL TRENDS. THE EXTRATROPICAL TRANSITION APPEARS TO BE A DIFFICULT ONE TO FORECAST...WITH THE MAIN DISAGREEMENT BEING WHETHER PHILIPPE WILL BECOME THE MAIN NON-TROPICAL LOW OR BECOME ABSORBED INTO THE LARGER EXTRATROPICAL CYCLONE. GIVEN THE SMALL SIZE OF PHILIPPE...THE NHC FORECAST WILL GO WITH THE ABSORBED SCENARIO. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 24.7N 60.8W 55 KT 65 MPH 12H 05/1800Z 25.3N 61.4W 55 KT 65 MPH 24H 06/0600Z 26.5N 61.2W 60 KT 70 MPH 36H 06/1800Z 27.8N 60.1W 65 KT 75 MPH 48H 07/0600Z 28.9N 58.2W 60 KT 70 MPH 72H 08/0600Z 31.5N 52.0W 55 KT 65 MPH 96H 09/0600Z 38.0N 46.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 10/0600Z...ABSORBED $$ FORECASTER BLAKE NNNN
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Page last modified: Tuesday, 17-Jul-2012 13:44:07 UTC