ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM LESLIE DISCUSSION NUMBER 47 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 1100 PM AST MON SEP 10 2012 THE OVERALL CLOUD PATTERN HAS NOT CHANGED MUCH SINCE THE PREVIOUS ADVISORY OTHER THAN CLOUD TOPS HAVE COOLED SLIGHTLY TO THE NORTH AND EAST OF THE CENTER. AN EARLIER ASCAT OVERPASS INDICATED THAT LESLIE HAS WINDS OF AT LEAST 60 KT TO THE NORTH AND NORTHEAST OF THE CENTER. HOWEVER...RECENT DATA FROM CANADIAN BUOY 44139 LOCATED ABOUT 100 NMI NORTH-NORTHEAST OF THE CENTER SUGGEST THAT THE MAXIMUM WINDS ASSOCIATED WITH LESLIE HAVE LIKELY SHIFTED TO THE EAST AND SOUTHEAST OF THE CENTER SINCE THE WINDS AT THAT BUOY HAVE NOT INCREASED TO MORE THAN 25 KT. THE ASYMMETRY OF THE WINDFIELD AND THE CONVECTIVE PATTERN IS MORE INDICATIVE OF AN EXTRATROPICAL RATHER THAN A TROPICAL CYCLONE DUE TO A STRONG COLD FRONTAL SYSTEM NOW LOCATED ONLY ABOUT 100 NMI WEST OF THE CENTER. IT IS QUITE POSSIBLE THAT THE FRONTAL SYSTEM WILL CATCH UP TO AND MERGE WITH THE CIRCULATION CENTER BEFORE LESLIE REACHES NEWFOUNDLAND. REGARDLESS OF THE STATUS OF THE CYCLONE AT LANDFALL TUESDAY MORNING...IT WILL STILL BE A POWERFUL LOW PRESSURE SYSTEM. ONCE LESLIE BECOMES POST-TROPICAL...IT WILL REMAIN A VERY STRONG EXTRATROPICAL CYCLONE FOR THE NEXT FEW DAYS OVER THE COLD WATERS OF THE FAR NORTH ATLANTIC. LESLIE HAS CONTINUED TO ACCELERATE AND IS NOW MOVING TOWARD THE NORTH-NORTHEAST AT ABOUT 35 KT. THE CYCLONE IS EMBEDDED IN STRONG SOUTH-SOUTHWESTERLY DEEP-LAYER FLOW AHEAD OF A VIGOROUS NEGATIVELY TILTED MID-LATITUDE TROUGH THAT IS ORIENTED NORTHWEST-TO-SOUTHEAST ACROSS MAINE AND THE CANADIAN MARITIMES. AN ADDITIONAL INCREASE IN FORWARD SPEED IS ANTICIPATED AS THE TROUGH LIFTS OUT TO THE NORTHEAST...AND THE CENTER OF LESLIE IS FORECAST TO MAKE LANDFALL OVER SOUTHEASTERN NEWFOUNDLAND IN ABOUT 12 HOURS OR SO. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND LIES CLOSE TO THE DYNAMICAL CONSENSUS MODELS TVCN AND TV15. LONG-PERIOD SWELLS FROM LESLIE ARE STILL EXPECTED TO PRODUCE ROUGH SURF AND LIFE-THREATENING RIP CURRENTS ON BERMUDA AND ALONG MUCH OF THE U.S. EAST COAST...AND THE CANADIAN ATLANTIC PROVINCES. FORECAST POSITIONS AND MAX WINDS INIT 11/0300Z 42.7N 57.5W 60 KT 70 MPH 12H 11/1200Z 47.6N 54.1W 60 KT 70 MPH...INLAND 24H 12/0000Z 54.2N 47.2W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 12/1200Z 59.8N 38.6W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 13/0000Z 62.5N 29.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 14/0000Z 62.5N 10.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 15/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ FORECASTER STEWART NNNN
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Page last modified: Monday, 31-Dec-2012 12:09:34 UTC