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#449664 (Received by flhurricane at: 4:34 PM 13.Aug.2011) TCDAT1 TROPICAL STORM FRANKLIN DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011 500 PM EDT SAT AUG 13 2011 AFTER THE MORNING FLARE UP OF DEEP CONVECTION NEAR THE CENTER OF FRANKLIN...INCREASING VERTICAL SHEAR AND COLDER WATER HAVE STARTED TAKING THEIR TOLL ON THE CYCLONE THIS AFTERNOON. CONVECTION IS NOW SHEARED MORE THAN 90 NMI FROM THE CENTER AND THE LOW-LEVEL CENTER HAS BECOME FULLY EXPOSED. FRANKLIN IS QUICKLY TAKING ON THE APPEARANCE OF A POST TROPICAL/EXTRATROPICAL LOW PRESSURE SYSTEM. THE INITIAL INTENSITY IS DECREASED TO 35 KT BASED ON A TAFB SATELLITE DATA-T NUMBER OF T2.5/35 KT. THE INITIAL MOTION ESTIMATE IS NOW 070/19. FRANKLIN SHOULD CONTINUE TO GRADUALLY TURN TOWARD THE EAST AS IT REMAINS EMBEDDED WITHIN WESTERLY LOW- TO MID-LEVEL FLOW AHEAD OF A MID-TROPOSPHERIC TROUGH. AS THE CYCLONE WEAKENS AND BECOMES MORE VERTICALLY SHALLOW... FRANKLIN SHOULD DECELERATE AND BE STEERED TOWARD THE EAST-SOUTHEAST BY WEAKER LOW-LEVEL FLOW IN THE LATTER FORECAST PERIODS. THE NHC FORECAST TRACK IS SIMILAR TO BUT SLIGHTLY SOUTH AND SLOWER THAN THE PREVIOUS ADVISORY...AND CLOSELY FOLLOWS THE NHC DYNAMICAL MODEL CONSENSUS. FRANKLIN IS CURRENTLY OVER 25C SST WATER AND COOLER WATER LIES AHEAD OF THE CYCLONE FOR AT LEAST THE NEXT 36 HOURS. THE COMBINATION OF INCREASING WESTERLY VERTICAL WIND SHEAR AND COLDER WATER SHOULD INHIBIT THE DEVELOPMENT OF ANY SIGNIFICANT DEEP CONVECTION NEAR THE EXPOSED LOW-LEVEL CENTER. AS A RESULT...FRANKLIN COULD BECOME FULLY EXTRATROPICAL WITHIN THE NEXT 12 HOURS OR SO. THE POST-TROPICAL REMNANT LOW IS THEN EXPECTED TO MERGE WITH A COLD FRONT IN 24 HOURS...AND IT STILL APPEARS THAT THERE WILL NOT BE ENOUGH BAROCLINIC ENERGY TO CAUSE FRANKLIN TO RE-STRENGTHEN AS A SIGNIFICANT EXTRATROPICAL LOW PRESSURE SYSTEM. THE INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND REMAINS LOWER THAN ALL OF THE NHC INTENSITY GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 39.7N 55.5W 35 KT 40 MPH 12H 14/0600Z 40.2N 51.9W 35 KT 40 MPH...POST-TROP/EXTRATROP 24H 14/1800Z 40.3N 47.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 36H 15/0600Z 39.9N 43.3W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 15/1800Z 38.8N 40.7W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 16/1800Z...DISSIPATED $$ FORECASTER STEWART |