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Tropical Storm LESLIE


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TROPICAL STORM LESLIE DISCUSSION NUMBER  22
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
500 PM AST TUE SEP 04 2012
 
ALTHOUGH DEEP CONVECTION HAS REDEVELOPED NEAR THE CENTER OF LESLIE
DURING THE DAY...THE LOW-LEVEL CENTER IS STILL SOMEWHAT DISPLACED
TO THE WEST OF THE MID- AND UPPER-LEVEL CENTER. THE CI-NUMBERS FROM
TAFB AND SAB REMAIN 3.5 AND A RECENT ASCAT PASS SHOWED
BIAS-CORRECTED WINDS OF 50-55 KT...SO THE INITIAL INTENSITY IS HELD
AT 55 KT. 20 KT OF WEST-NORTHWESTERLY VERTICAL WIND SHEAR...AS
ANALYZED BY THE UW-CIMSS AND SHIPS SHEAR ANALYSIS...CONTINUES TO BE
THE PRIMARY INHIBITING FACTOR FOR DEVELOPMENT. THE SHEAR IS
FORECAST TO RELAX AFTER 36 HOURS...WHICH SHOULD ALLOW FOR
INTENSIFICATION. ADDITIONALLY...THE UNIVERSITY OF MIAMI-RSMAS OCEAN
ANALYSIS INDICATES THAT THE HEAT CONTENT OF THE OCEAN BELOW LESLIE
IS HIGH...WHICH MAY LIMIT THE IMPACTS OF COLD WATER UPWELLING FROM
THE SLOW-MOVING CYCLONE. THE FORECAST CALLS FOR STEADY
INTENSIFICATION AFTER 36 HOURS...AND IS CLOSE TO THE LGEM MODEL
FORECAST. BY DAY 5...THE OFFICIAL FORECAST IS HIGHER THAN MOST OF
THE NUMERICAL GUIDANCE...HOWEVER...GIVEN THE EXPECTED FAVORABLE
ENVIRONMENT AROUND THE CYCLONE...THE INTENSITY FORECAST HAS NOT
BEEN ADJUSTED DOWN AT THIS TIME.
 
WHILE THE CENTER HAS WOBBLED SLIGHTLY TO THE WEST DURING THE
DAY...LESLIE CONTINUES TO DRIFT GENERALLY NORTHWARD AND THE LONG-
TERM INITIAL MOTION IS ESTIMATED AT 360/3. THIS TRACK IS EXPECTED
TO CONTINUE FOR THE NEXT COUPLE OF DAYS UNTIL A RIDGE BEGINS TO
BUILD TO THE NORTHEAST OF THE TROPICAL CYCLONE...IMPARTING A MORE
NORTHWESTERLY MOTION. LESLIE SHOULD FINALLY BEGIN TO ACCELERATE AS
IT MOVES AROUND THIS RIDGE ON DAYS 4 AND 5. THE GLOBAL AND REGIONAL
DYNAMICAL MODELS ARE SHOWING A SLIGHTLY SLOWER AND WESTWARD TRACK
THIS CYCLE AND THE OFFICIAL FORECAST HAS BEEN NUDGED ACCORDINGLY.

THE 34- AND 50-KT WIND RADII WERE MODIFIED BASED ON A 1320 UTC ASCAT
PASS.
 
DUE TO THE LARGE SIZE OF LESLIE AND ITS EXPECTED SLOW MOTION...
LARGE SWELLS PROPAGATING AWAY FROM THE TROPICAL CYCLONE WILL
CONTINUE TO AFFECT BERMUDA AND NEARLY ALL OF THE U.S. EAST
COAST FOR MUCH OF THIS WEEK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/2100Z 25.3N  62.6W   55 KT  65 MPH
 12H  05/0600Z 25.7N  62.7W   55 KT  65 MPH
 24H  05/1800Z 26.1N  62.7W   55 KT  65 MPH
 36H  06/0600Z 26.5N  62.7W   55 KT  65 MPH
 48H  06/1800Z 26.9N  62.8W   60 KT  70 MPH
 72H  07/1800Z 27.5N  63.5W   70 KT  80 MPH
 96H  08/1800Z 29.5N  65.0W   80 KT  90 MPH
120H  09/1800Z 34.0N  65.5W   90 KT 105 MPH
 
$$
FORECASTER ZELINSKY/CANGIALOSI
 
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