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Tropical Storm LEE (Text)

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TROPICAL STORM LEE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
400 PM CDT SAT SEP 03 2011
 
THE OVERALL CONVECTIVE ORGANIZATION OF LEE HAS NOT CHANGED SINCE THE
PREVIOUS ADVISORY. ALTHOUGH DOPPLER RADAR VELOCITIES ONLY SUPPORT
ABOUT 45 KT SURFACE WINDS...THE ASSUMPTION IS THAT STRONGER WINDS
EXIST IN THE DEEP CONVECTION IN THE SOUTHEAST QUADRANT OF THE
CIRCULATION THAT RECON AIRCRAFT WAS UNABLE TO INVESTIGATE THIS
AFTERNOON...AND WHICH LIES BEYOND THE RANGE OF THE GROUND-BASED
RADARS. SINCE THE PRESSURE HAS CONTINUED TO DROP AND IS NOW DOWN TO
989 MB...THE INITIAL INTENSITY IS BEING MAINTAINED AT 50 KT.

THE TWO LOW-LEVEL CIRCULATION CENTERS MENTIONED IN THE PREVIOUS
ADVISORY APPEAR TO HAVE CONSOLIDATED INTO ONE MAIN VORTEX NOW NEAR
MARSH ISLAND LOUISIANA. BASED ON THIS POSITION...THE INITIAL MOTION
ESTIMATE IS AN UNCERTAIN 360/03 KT. THE LATEST GLOBAL AND REGIONAL
MODELS...EXCLUDING THE HWRF MODEL...ARE IN MUCH BETTER AGREEMENT
NOW AND ARE SIMILAR TO THE PREVIOUS ECMWF MODEL SOLUTIONS. A
SHORTWAVE TROUGH OVER THE SOUTHERN AND CENTRAL U.S. PLAINS IS
EXPECTED TO MOVE SLOWLY EASTWARD AND ERODE THE WESTERN PORTION OF A
BLOCKING HIGH...WHICH WILL ALLOW LEE TO MOVE SLOWLY NORTHWARD FOR
THE NEXT 24 HOURS OR SO. AFTER THAT...HOWEVER...THE TROUGH IS
FORECAST TO BYPASS LEE AND LEAVE THE CYCLONE EMBEDDED ONCE AGAIN IN
WEAK STEERING FLOW. BY 72 HOURS...A SECOND TROUGH AND ASSOCIATED
COLD FRONT IS FORECAST TO NUDGE LEE SLOWLY TO THE NORTHEAST...AND
BEGIN TO INDUCE EXTRATROPICAL TRANSITION AS THE UPPER-LEVEL TROUGH
EVOLVES INTO A LARGE CUTOFF LOW OVER THE TENNESSEE AND OHIO VALLEYS
BY DAYS 4 AND 5. THE OFFICIAL FORECAST TRACK IS A LITTLE TO THE
RIGHT OF THE PREVIOUS ADVISORY TRACK...AND LIES BETWEEN THE NHC
MODEL CONSENSUS TRACK AND THE ECMWF TRACK.
 
SINCE THE CENTRAL PRESSURE HAS CONTINUED TO DECREASE...IT IS
POSSIBLE THAT LEE COULD STRENGTHEN SLIGHTLY WHEN CLOUD TOPS ARE
EXPECTED TO COOL IN THE LARGE BAND IN THE EASTERN SEMICIRCLE.
HOWEVER...THE OVERALL TREND CALLS FOR LEE TO REMAIN STEADY FOR THE
NEXT 12-24 HOURS...AND THEN SLOWLY WEAKEN AFTER THAT.
 
IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK OR WHERE
THE CENTER OF LEE EVENTUALLY MAKES LANDFALL SINCE THE STRONGEST
WINDS AND HEAVIEST RAINS EXTEND FAR FROM THE CENTER.

FORECAST POSITIONS AND MAX WINDS
 
INIT  03/2100Z 29.4N  92.1W   50 KT  60 MPH
 12H  04/0600Z 29.8N  91.9W   50 KT  60 MPH...INLAND
 24H  04/1800Z 30.2N  91.5W   50 KT  60 MPH...INLAND
 36H  05/0600Z 30.5N  91.1W   45 KT  50 MPH...INLAND
 48H  05/1800Z 31.2N  89.9W   40 KT  45 MPH...INLAND
 72H  06/1800Z 33.0N  87.2W   30 KT  35 MPH...INLAND
 96H  07/1800Z 34.5N  85.2W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  08/1800Z 37.0N  83.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 
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