Tropical Storm LESLIE

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TROPICAL STORM LESLIE DISCUSSION NUMBER  43
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
1100 PM AST SUN SEP 09 2012

CORRECTED FRIDAY TO MONDAY IN LAST PARAGRAPH 
 
THE CONVECTIVE CLOUD PATTERN OF LESLIE HAS CONTINUED TO SLOWLY ERODE
AND CLOUD TOPS HAVE ALSO CONTINUED TO WARM SINCE THE PREVIOUS
ADVISORY. THE INITIAL INTENSITY REMAINS AT 50 KT BASED ON A BLEND
OF DVORAK SATELLITE INTENSITY ESTIMATES OF T3.0/45 KT AND T3.5/55
KT FROM TAFB AND SAB...RESPECTIVELY. 
 
THE INITIAL MOTION ESTIMATE IS 015/14. THERE REMAINS NO SIGNIFICANT
CHANGE TO THE PREVIOUS TRACK FORECAST AND REASONING. LESLIE IS
EXPECTED TO CONTINUE MOVING NORTH-NORTHEASTWARD FOR THE NEXT 12
HOURS OR SO AS THE CYCLONE ROUNDS THE WESTERN PERIPHERY OF A
DEEP-LAYER RIDGE LOCATED TO ITS EAST. BY 24 HOURS...LESLIE IS
FORECAST TO ACCELERATE TO THE NORTHEAST BETWEEN INCREASING
SOUTHWESTERLY FLOW AHEAD OF AN APPROACHING DEEP-LAYER TROUGH FROM
THE WEST AND THE AFOREMENTIONED RIDGE TO THE EAST. BY DAYS 3-4...
LESLIE WILL BE INTERACTING WITH A FRONTAL SYSTEM...AND THE
POST-TROPICAL CYCLONE IS EXPECTED TURN EAST-NORTHEASTWARD AND
EASTWARD IN THE HIGH-LATITUDE WESTERLY FLOW. ABSORPTION BY A LARGER
EXTRATROPICAL LOW IS FORECAST TO OCCUR BY DAY 5 OVER THE NORTH SEA.
THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MIDDLE OF THE TIGHTLY
PACKED NHC MODEL GUIDANCE.

LESLIE CONTINUES TO LACK ANY INNER-CORE DEEP CONVECTION AND ALSO HAS
A BROAD INNER-CORE WIND FIELD...WHICH SHOULD INHIBIT ANY
SIGNIFICANT STRENGTHENING IN THE SHORT TERM. HOWEVER...AS THE
CYCLONE BEGINS TO ACCELERATE RAPIDLY NORTHEASTWARD...THE ADDITIONAL
FORWARD SPEED COMPONENT SHOULD INCREASE THE WIND SPEEDS IN THE
EASTERN SEMICIRCLE. SINCE LESLIE IS FORECAST TO BE MOVING AT NEARLY
35 KT BY 36 HOURS...THIS COULD ALLOW THE CYCLONE TO ACHIEVE
HURRICANE STATUS AGAIN BEFORE THE CYCLONE AFFECTS SOUTHEASTERN
NEWFOUNDLAND. AFTER 36 HOURS...THE GLOBAL MODELS INDICATE THAT
LESLIE WILL TRANSITION INTO A VIGOROUS EXTRATROPICAL CYCLONE AFTER
IT MERGES WITH A STRONG FRONTAL SYSTEM BY DAY 2. LESLIE WILL REMAIN
A POWERFUL EXTRATROPICAL CYCLONE UNTIL IT IS ABSORBED BY A LARGER
EXTRATROPICAL LOW PRESSURE SYSTEM ON DAY 5.
 
LONG-PERIOD SWELLS FROM LESLIE ARE EXPECTED TO PRODUCE ROUGH SURF
AND LIFE-THREATENING RIP CURRENTS ON BERMUDA AND ALONG MUCH OF THE
U.S. EAST COAST FOR THE NEXT COUPLE OF DAYS. OWING TO THE INCREASING
FORWARD SPEED OF LESLIE FOR THE NEXT 36 HOURS...A HURRICANE WATCH
WILL LIKELY REQUIRED EARLY MONDAY MORNING FOR PORTIONS OF
SOUTHEASTERN NEWFOUNDLAND...INCLUDING THE AVALON PENINSULA.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/0300Z 34.4N  61.8W   50 KT  60 MPH
 12H  10/1200Z 36.8N  60.8W   55 KT  65 MPH
 24H  11/0000Z 41.3N  58.2W   60 KT  70 MPH
 36H  11/1200Z 47.5N  53.9W   65 KT  75 MPH...INLAND
 48H  12/0000Z 54.1N  46.7W   60 KT  70 MPH...POST-TROP/EXTRATROP
 72H  13/0000Z 62.5N  25.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
 96H  14/0000Z 62.5N   3.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  15/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW
 
$$
FORECASTER STEWART
 
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