000
WTNT42 KNHC 070234
TCDAT2
 
HURRICANE LESLIE DISCUSSION NUMBER  31
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
1100 PM AST THU SEP 06 2012

THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE SATELLITE APPEARANCE OF
LESLIE DURING THE PAST SEVERAL HOURS...WITH THE SYSTEM CONTINUING
TO FEATURE A CENTRAL DENSE OVERCAST WITH CLOUD TOPS COLDER
THAN -70C.  HOWEVER...MICROWAVE IMAGES PRIOR TO 0000 UTC DID NOT
SHOW A WELL-DEFINED EYE OR EYEWALL.  SATELLITE INTENSITY ESTIMATES
FROM TAFB AND SAB ARE 65 KT...WHILE SATELLITE CONSENSUS INTENSITY
ESTIMATES FROM CIMSS ARE 60-65 KT.  THE INITIAL INTENSITY REMAINS
65 KT FOR THIS ADVISORY.  THE CIRRUS OUTFLOW IS GOOD IN THE EASTERN
SEMICIRCLE AND IMPROVING IN THE WESTERN SEMICIRCLE.

LESLIE HAS MOVED LITTLE DURING THE PAST SEVERAL HOURS AS IT REMAINS
IN AN AREA OF LIGHT-TO-NON-EXISTENT STEERING CURRENTS.  WATER VAPOR
IMAGERY SHOWS A SHORTWAVE RIDGE IN THE WESTERLIES NORTH OF THE
HURRICANE.  THIS FEATURE IS EXPECTED TO MOVE EAST DURING THE NEXT
12-24 HR AND ALLOW LESLIE TO BEGIN A SLOW NORTHWARD MOTION.  IN THE
LONGER TERM...THE GLOBAL MODELS FORECAST A DEEP-LAYER TROUGH AND
ASSOCIATED SURFACE FRONTAL SYSTEM TO MOVE EASTWARD THROUGH THE
EASTERN UNITED STATES AND REACH THE WESTERN ATLANTIC BY 72 HR. 
THIS SYSTEM SHOULD STEER LESLIE NORTHWARD AND THEN EVENTUALLY
NORTH-NORTHEASTWARD.  HOWEVER...THERE IS SOME SPREAD IN THE
GUIDANCE IN THE FORWARD SPEED...WITH THE CANADIAN MODEL NOTABLY
FASTER THAN THE OTHER GUIDANCE...AND THE GFS SOMEWHAT SLOWER THAN
THE OTHER GUIDANCE.  THE FORECAST TRACK AFTER 36 HR COMPROMISES
BETWEEN THESE EXTREMES AND LIES NEAR THE VARIOUS CONSENSUS MODELS. 
THE GUIDANCE ENVELOPE HAS CHANGED LITTLE SINCE THE LAST ADVISORY...
AND THUS THE NEW FORECAST TRACK IS CLOSE TO THE PREVIOUS FORECAST.

LESLIE HAS MOVED SLOWLY ENOUGH FOR THE PAST TWO DAYS TO HAVE
UPWELLED COLD OCEAN WATER TO THE SURFACE.  REPORTS FROM NOAA BUOY
41049 INDICATE THAT THE SEA SURFACE TEMPERATURE HAS DECREASED FROM
29C TO 26C-27C...WHILE MICROWAVE-BASED SEA SURFACE TEMPERATURE
ESTIMATES SUGGEST TEMPERATURES OF 24C-25C UNDER THE CORE OF THE
HURRICANE.  AT BEST...LITTLE INTENSIFICATION SHOULD OCCUR UNTIL
LESLIE MOVES NORTH OF THE COLD WATER...AND SOME WEAKENING IS
POSSIBLE.  THE NEW INTENSITY FORECAST FROM 12-36 HR IS REDUCED FROM
THAT OF THE PREVIOUS ADVISORY BASED ON THE PRESENCE OF THE COLD
WATER.  FROM 36-72 HR...LESLIE SHOULD MOVE OVER WARMER WATERS AND
STRENGTHEN...AND THE NEW FORECAST IS SIMILAR TO THE PREVIOUS
FORECAST DURING THIS TIME.  INCREASING SHEAR AND THE START OF
EXTRATROPICAL TRANSITION SHOULD LEAD TO WEAKENING AFTER THE 72 HR
POINT.
 
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 FOR THE REMAINDER OF THIS WEEK.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0300Z 26.5N  62.2W   65 KT  75 MPH
 12H  07/1200Z 26.8N  62.2W   65 KT  75 MPH
 24H  08/0000Z 27.2N  62.4W   65 KT  75 MPH
 36H  08/1200Z 28.0N  62.6W   70 KT  80 MPH
 48H  09/0000Z 29.3N  62.6W   80 KT  90 MPH
 72H  10/0000Z 33.0N  61.5W   90 KT 105 MPH
 96H  11/0000Z 37.0N  59.0W   80 KT  90 MPH
120H  12/0000Z 43.0N  55.5W   70 KT  80 MPH
 
$$
FORECASTER BEVEN