Tropical Storm LESLIE

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TROPICAL STORM LESLIE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
500 AM AST SAT SEP 01 2012
 
LESLIE CONTINUES TO PRODUCE A LARGE CENTRAL DENSE OVERCAST WITH A
BAND OF DEEP CONVECTION WRAPPING AROUND THE SOUTHERN AND WESTERN
SEMICIRCLES.  DURING THE PAST FEW HOURS...AN EYE-LIKE FEATURE WAS
OBSERVED IN INFRARED SATELLITE IMAGERY EMBEDDED IN THE CENTER OF
THE CDO.  HOWEVER...THERE HAVE BEEN NO TIMELY MICROWAVE PASSES...
AND IT IS UNCLEAR IF THIS FEATURE IS COINCIDENT WITH THE LOW-LEVEL
CENTER.  STILL...DVORAK ESTIMATES HAVE COME UP TO T4.0 FROM TAFB
AND T3.5 FROM SAB...AND THE INITIAL INTENSITY IS RAISED TO 60 KT.

DESPITE THE UNCERTAINTY IN THE CENTER LOCATION...THE INITIAL MOTION
APPEARS TO BE A LITTLE SLOWER THAN BEFORE AND IS ESTIMATED TO BE
295/15 KT.  A DIGGING SHORTWAVE TROUGH OVER THE WESTERN ATLANTIC IS
EXPECTED TO DEVELOP A CUT-OFF LOW DURING THE NEXT 24 HOURS...AND
THIS SHOULD CAUSE THE RIDGE TO THE NORTH OF LESLIE TO WEAKEN. 
LESLIE WILL RESPOND BY TURNING NORTHWESTWARD AND THEN NORTHWARD
DURING THE NEXT 5 DAYS...BUT THE CYCLONE WILL ALSO SLOW DOWN AS THE
STEERING FLOW AROUND IT COLLAPSES.  ALTHOUGH THERE IS SOME
DIVERGENCE IN THE TRACK GUIDANCE AFTER ABOUT 72 HOURS...THEY ALL
SHOW A SLOW MOTION TOWARD THE NORTH OR EVEN NORTH-NORTHEAST BY DAY
5.  THE NEW NHC FORECAST LIES ON THE WESTERN SIDE OF THE GUIDANCE
ENVELOPE...AND IS NUDGED SLIGHTLY EAST OF THE PREVIOUS FORECAST ON
DAYS 4 AND 5.

IF LESLIE IS GOING TO STRENGTHEN...IT PROBABLY HAS TO DO IT DURING
THE NEXT 24 TO 48 HOURS BEFORE IT ENCOUNTERS STRONG WESTERLY TO
NORTHWESTERLY SHEAR.  THE UPPER-LEVEL PATTERN COULD THEN BECOME
MORE FAVORABLE FOR STRENGTHENING BY DAY 5.  THE INTENSITY MODELS DO
NOT SUPPORT MUCH INTENSIFICATION DURING THE FORECAST PERIOD...AND
THE NEW NHC FORECAST IS LARGELY UNCHANGED FROM THE PREVIOUS ONE BY
INDICATING ONLY GRADUAL STRENGTHENING.  THIS FORECAST IS HIGHER
THAN THAT SHOWN BY THE STATISTICAL GUIDANCE...BUT NOT AS HIGH AS
THE INTENSITY CONSENSUS ICON AND HFIP CONSENSUS TV15.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0900Z 17.8N  53.5W   60 KT  70 MPH
 12H  01/1800Z 18.8N  55.5W   65 KT  75 MPH
 24H  02/0600Z 20.2N  57.7W   65 KT  75 MPH
 36H  02/1800Z 21.6N  59.5W   65 KT  75 MPH
 48H  03/0600Z 23.1N  60.8W   70 KT  80 MPH
 72H  04/0600Z 25.0N  61.5W   70 KT  80 MPH
 96H  05/0600Z 26.5N  61.5W   70 KT  80 MPH
120H  06/0600Z 28.5N  61.0W   75 KT  85 MPH
 
$$
FORECASTER BERG
 
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