Tropical Storm LESLIE

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TROPICAL STORM LESLIE DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
1100 AM AST FRI AUG 31 2012
 
LESLIE CONTINUES TO EXPERIENCE NORTHEASTERLY SHEAR...WHICH IS
CAUSING MOST OF THE CONVECTION TO BE LOCATED IN THE SOUTHWESTERN
QUADRANT OF THE STORM.  THIS STRUCTURE IS CONFIRMED BY RECENT
MICROWAVE PASSES AND VISIBLE SATELLITE IMAGERY THAT SHOW THE CENTER
EMBEDDED IN THE NORTHERN PORTION OF A SMALL CENTRAL DENSE OVERCAST
FEATURE.  THE INTENSITY ESTIMATES HAVE NOT CHANGED MUCH...SO THE
WIND SPEED IS KEPT AT 55 KT.  THE SHEAR HAS BEEN A LITTLE STRONGER
THAN PREVIOUSLY ANTICIPATED...AND MICROWAVE IMAGES SUGGEST THAT
LESLIE LACKS ANY CENTRAL CORE.  GIVEN THESE FACTORS...THE INTENSITY
FORECAST HAS BEEN REDUCED A BIT FROM THE PREVIOUS ONE IN THE SHORT
TERM.  WHILE THE GLOBAL MODELS ARE STILL SHOWING A LARGE UPPER-LEVEL
ANTICYCLONE NEAR LESLIE IN A FEW DAYS...THE POSITIONING OF LESLIE
WITHIN THAT ANTICYCLONE APPEARS LESS FAVORABLE THAN YESTERDAY...
WITH WESTERLY SHEAR POSSIBLE.  THE INTENSITY CONSENSUS IS QUITE A
BIT LOWER THAN A COUPLE MODEL CYCLES AGO...AND THIS TOOL HAS BEEN A
GOOD PERFORMER THIS YEAR.  THE NEW FORECAST IS A BLEND OF THE
PREVIOUS INTERPOLATED FORECAST AND THE INTENSITY CONSENSUS...AND
RESULTS IN A REDUCTION TO THE NHC WIND SPEED PREDICTION.

THE INITIAL MOTION ESTIMATE IS 295/15...A BIT FASTER AND TO THE
RIGHT OF THE PREVIOUS ONE.  LESLIE REMAINS BASICALLY ON TRACK AS IT
MOVES BENEATH A NARROW RIDGE TO THE SOUTH OF HURRICANE KIRK.  THE
RIDGE BREAKS BETWEEN 60W-65W...WHICH SHOULD CAUSE THE STORM TO TURN
TOWARD THE NORTHWEST AND NORTH WITH A LARGE DECREASE IN FORWARD
SPEED IN A FEW DAYS.  THE GLOBAL MODELS ARE WELL CLUSTERED ON THE
TRACK THROUGH THE FIRST 48 HOURS...AND ONLY SMALL CHANGES WERE MADE
TO THE NHC FORECAST UP TO THAT TIME.  IT NOW APPEARS THAT LESLIE
WILL MISS A TROUGH FORECAST TO DIVE OFFSHORE OF NORTH AMERICA...AND
WILL BE CAUGHT IN AN AREA OF LIGHT STEERING CURRENTS IN THE LONG
RANGE.  THE MODELS CONTINUE TO SLOW DOWN AT DAYS 4 AND 5...AND THE
NHC FORECAST IS SHIFTED SLIGHTLY TO THE SOUTH AND WEST AT THOSE
TIMES.  


 
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/1500Z 16.2N  49.1W   55 KT  65 MPH
 12H  01/0000Z 17.2N  51.3W   60 KT  70 MPH
 24H  01/1200Z 18.5N  54.0W   65 KT  75 MPH
 36H  02/0000Z 19.6N  56.3W   70 KT  80 MPH
 48H  02/1200Z 20.9N  58.4W   75 KT  85 MPH
 72H  03/1200Z 23.8N  61.3W   80 KT  90 MPH
 96H  04/1200Z 25.9N  62.2W   75 KT  85 MPH
120H  05/1200Z 27.0N  62.5W   75 KT  85 MPH
 
$$
FORECASTER BLAKE
 
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