000
WTNT42 KNHC 110258
TCDAT2

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