Hurricane LESLIE

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HURRICANE LESLIE DISCUSSION NUMBER  26
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
500 PM AST WED SEP 05 2012
 
THE CIRRUS OUTFLOW OF LESLIE HAS EXPANDED BY MORE THAN 100 NMI TO
THE WEST SINCE THE PREVIOUS ADVISORY...INDICATING THAT THE VERTICAL
WIND SHEAR AFFECTING THE CYCLONE HAS DECREASED. A BANDING EYE
FEATURE HAS BEEN EVIDENT IN VISIBLE SATELLITE IMAGERY SINCE 1700
UTC...BUT A RECENT BURST OF EYEWALL CONVECTION HAS OBSCURED THE
EYE. SSMIS AND TRMM MICROWAVE DATA INDICATE A WELL-DEFINED
MID-LEVEL EYE HAS DEVELOPED AND A CONCENTRIC EYEWALL CYCLE COULD
BE UNDERWAY. THE INITIAL INTENSITY OF 65 KT IS BASED ON SATELLITE
INTENSITY ESTIMATES OF T4.0/65 KT FROM TAFB AND SAB...AND AN
AVERAGE ADT ESTIMATE OF T4.3/72 KT OVER THE PAST 6 HOURS.
 
THE INITIAL MOTION ESTIMATE REMAINS 360/02 KT. LESLIE HAS WOBBLED
SLIGHTLY TO THE NORTHEAST SINCE THE PREVIOUS ADVISORY...BUT THAT
ERRATIC MOTION IS LIKELY JUST DUE TO REFORMATION OF THE EYE. THE
LATEST GFS FORECAST TRACK HAS SHIFTED A LITTLE TO THE WEST...WHILE
THE ECMWF FORECAST HAS SHIFTED TO THE EAST. SINCE THESE TWO MODELS
ARE NOW CONVERGING CLOSER TO THE PREVIOUS FORECAST TRACK...THE NEW
NHC FORECAST IS JUST AN UPDATE OF THE PREVIOUS ADVISORY...WHICH
LIES A LITTLE TO THE EAST OF THE CONSENSUS MODELS TVCA AND TV15.
 
CONDITIONS ARE EXPECTED TO BE FAVORABLE FOR AT LEAST GRADUAL
STRENGTHENING TO OCCUR FOR THE NEXT 96 HOURS. COLD WATER UPWELLING
BENEATH THE CYCLONE DUE TO ITS VERY SLOW FORWARD SPEED AND THE
PRESENCE OF DRY MID-LEVEL AIR LURKING JUST TO THE WEST OF THE
CYCLONE MAY LIMIT THE RATE OF INTENSIFICATION. THE GFS-BASED SHIPS
AND LGEM MODELS CONTINUE TO HAVE NEGATIVE FEEDBACK ISSUES AS A
RESULT OF THE GFS MODEL CREATING A VERY ROBUST HURRICANE...WHICH
FURTHER GENERATES SIGNIFICANT 200 MB WARMING AFTER 72 HOURS. THE
ECMWF... UKMET...AND HWRF MODELS ALSO CONTINUE TO PRODUCE A STRONG
HURRICANE THROUGHOUT THE FORECAST PERIOD. THE OFFICIAL INTENSITY
FORECAST IS VERY SIMILAR TO THE PREVIOUS ADVISORY AND REMAINS
REMAINS HIGHER THAN MOST OF THE INTENSITY GUIDANCE AFTER 72 HOURS.
 
LESLIE IS A LARGE TROPICAL CYCLONE THAT IS FORECAST TO GROW IN SIZE
OVER THE NEXT SEVERAL DAYS. THE WIND FIELD OF THE CYCLONE...
COMBINED WITH ITS EXPECTED SLOW MOTION...WILL HELP TO GENERATE
LARGE LONG-PERIOD SWELLS THAT WILL PROPAGATE AWAY FROM THE TROPICAL
CYCLONE TOWARD BERMUDA AND MUCH OF THE U.S. EAST COAST FOR THE
REMAINDER OF THIS WEEK.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/2100Z 25.9N  62.7W   65 KT  75 MPH
 12H  06/0600Z 26.1N  62.8W   70 KT  80 MPH
 24H  06/1800Z 26.5N  63.0W   75 KT  85 MPH
 36H  07/0600Z 26.8N  63.1W   80 KT  90 MPH
 48H  07/1800Z 27.2N  63.4W   85 KT 100 MPH
 72H  08/1800Z 29.3N  64.4W   90 KT 105 MPH
 96H  09/1800Z 34.0N  64.4W   95 KT 110 MPH
120H  10/1800Z 42.0N  61.0W   85 KT 100 MPH
 
$$
FORECASTER STEWART
 
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