Tropical Storm LESLIE

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TROPICAL STORM LESLIE DISCUSSION NUMBER  33
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
1100 AM AST FRI SEP 07 2012
 
LESLIE HAS BEEN NEARLY STATIONARY TOO LONG AND THE OCEAN BENEATH HAS
COOLED SIGNIFICANTLY. IN FACT...ONE OF THE AXBT SONDES LAUNCHED FROM
THE NOAA PLANE CURRENTLY IN LESLIE MEASURED A SEA SURFACE
TEMPERATURE OF 24.5 DEGREES CELSIUS. CONSEQUENTLY...THE CONVECTION
HAS DIMINISHED AND THE CLOUD PATTERN HAS BECOME LESS ORGANIZED. THE
NOAA HURRICANE HUNTER AIRCRAFT ALSO MEASURED A MINIMUM PRESSURE OF
981 MB...BUT BOTH SFMR AND FLIGHT LEVEL WINDS ONLY SUPPORT AN
INITIAL INTENSITY OF 60 KNOTS.  ONCE LESLIE MOVES AWAY FROM THE
COOL POOL IT HAS CREATED FOR ITSELF...THE CYCLONE WILL HAVE THE
OPPORTUNITY TO REGAIN HURRICANE STATUS SINCE THE SHEAR IS EXPECTED
TO BE LOW.  BY THE END OF THE FORECAST PERIOD...LESLIE SHOULD HAVE
LOST TROPICAL CHARACTERISTICS AND BECOME A STRONG POST-TROPICAL 
CYCLONE.
 
THE STEERING CURRENTS COLLAPSED A COUPLE OF DAYS AGO RESULTING IN
LESLIE BEING NEARLY STATIONARY. GLOBAL MODELS ARE SHOWING A LARGE
MID-LEVEL TROUGH MOVING EASTWARD ACROSS THE EASTERN UNITED STATES
AND CANADA. THIS TROUGH SHOULD ACCELERATE THE SOUTHERLY FLOW THAT
EVENTUALLY WILL FORCE LESLIE TO MOVE NORTHWARD AND THEN
NORTH-NORTHEASTWARD WITH AN INCREASING FORWARD SPEED DURING THE
NEXT FEW DAYS. THE TRACK GUIDANCE IS MORE CONSISTENT WITH THIS
SOLUTION PRIMARILY IN THE FIRST 3 DAYS.  THE NHC FORECAST IS VERY
CLOSE TO THE MODEL CONSENSUS AND IS A BLEND OF THE GFS AND THE
ECMWF.
 
THE WIND FIELD OF LESLIE...COMBINED WITH ITS EXPECTED SLOW MOTION...
WILL GENERATE LONG-PERIOD SWELLS THAT WILL PRODUCE LARGE WAVES AND
LIFE-THREATENING RIP CURRENTS ON BERMUDA AND ALONG MUCH OF THE U.S.
EAST COAST THROUGH THE WEEKEND.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/1500Z 26.8N  62.2W   60 KT  70 MPH
 12H  08/0000Z 27.1N  62.2W   60 KT  70 MPH
 24H  08/1200Z 28.0N  62.2W   60 KT  70 MPH
 36H  09/0000Z 29.0N  62.2W   70 KT  80 MPH
 48H  09/1200Z 30.5N  61.9W   80 KT  90 MPH
 72H  10/1200Z 33.3N  60.8W   85 KT 100 MPH
 96H  11/1200Z 39.0N  57.0W   75 KT  85 MPH
120H  12/1200Z 45.5N  53.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER AVILA
 
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