Tropical Storm LESLIE

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TROPICAL STORM LESLIE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122012
1100 AM AST SAT SEP 01 2012
 
VISIBLE SATELLITE IMAGES SHOW THAT LESLIE REMAINS A SHEARED CYCLONE 
WITH THE LOW-LEVEL CENTER DISPLACED TO THE NORTHWEST OF THE MAIN
CONVECTIVE BAND.  THE INITIAL WIND SPEED IS KEPT AT 60 KT AS A
COMPROMISE BETWEEN THE VARIOUS INTENSITY ESTIMATES.  IT SEEMS LIKE
THE WINDOW FOR LESLIE TO BECOME A HURRICANE IS CLOSING AS
NORTHWESTERLY SHEAR HAS INCREASED.  THIS SHEAR IS EVIDENT IN CIRRUS
CLOUD MOTIONS NEAR THE CENTER...ALONG WITH LARGE-SCALE ANALYSES
FROM THE SHIPS MODEL AND UW-CIMSS.  THE GLOBAL MODELS SUGGEST
THIS SHEAR WILL PERSIST OR EVEN INTENSIFY DURING THE NEXT COUPLE OF
DAYS AS LESLIE IS CAUGHT ON THE EASTERN SIDE OF AN UPPER-LEVEL
ANTICYCLONE.  THE NHC INTENSITY FORECAST IS REDUCED DURING THAT
TIME...AND IS IN BEST AGREEMENT WITH THE INTENSITY CONSENSUS AND
THE FSU SUPERENSEMBLE.  THERE ARE SOME INDICATIONS THAT THE SHEAR
COULD RELAX IN A FEW DAYS...SO GRADUAL STRENGTHENING IS SHOWN IN
THE LONG RANGE...CONTINUING THE TREND OF THE PREVIOUS FORECAST.
 
MICROWAVE AND VISIBLE IMAGES REQUIRE A REPOSITIONING OF LESLIE ABOUT
30 N MI WEST OF THE PREVIOUS FIXES...GIVING A LONG-TERM MOTION OF
ABOUT 290/16.  THE CYCLONE SHOULD TURN TO THE NORTHWEST BY TOMORROW
AS IT MOVES AROUND A WEAKENING RIDGE OVER THE CENTRAL ATLANTIC
OCEAN...THEN TURN NORTHWARD IN A FEW DAYS AS IT NEARS A BREAK IN
THE RIDGE.  THE GLOBAL MODELS ARE A BIT FASTER IN GENERAL...SHOWING
ENOUGH RIDGING EAST OF LESLIE TO KEEP THE SYSTEM FROM TOTALLY
STALLING OUT AS SUGGESTED IN EARLIER MODEL CYCLES.  THE NEW NHC
FORECAST IS A BIT FASTER AND LEFT OF THE PREVIOUS ONE...MOSTLY DUE
TO THE CENTER REPOSITIONING.

THE INITIAL AND FORECAST WIND RADII WERE ADJUSTED BASED ON A 1244
UTC ASCAT PASS.
 

FORECAST POSITIONS AND MAX WINDS
 
INIT  01/1500Z 18.3N  55.7W   60 KT  70 MPH
 12H  02/0000Z 19.4N  57.6W   60 KT  70 MPH
 24H  02/1200Z 21.0N  59.8W   60 KT  70 MPH
 36H  03/0000Z 22.7N  61.2W   60 KT  70 MPH
 48H  03/1200Z 24.1N  62.1W   60 KT  70 MPH
 72H  04/1200Z 26.0N  62.5W   65 KT  75 MPH
 96H  05/1200Z 27.5N  62.0W   70 KT  80 MPH
120H  06/1200Z 29.0N  61.5W   75 KT  85 MPH
 
$$
FORECASTER BLAKE
 
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