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Tropical Depression LEE


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TROPICAL DEPRESSION LEE DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 PM CDT SUN SEP 04 2011
 
LAND INTERACTION AND CONTINENTAL AIR SEEN IN THE GOES SOUNDER
AIRMASS PRODUCT WRAPPING INTO THE WESTERN SIDE OF THE CIRCULATION
HAVE TAKEN A TOLL ON LEE THIS EVENING. DEEP CONVECTION HAS
DECREASED BOTH NEAR THE CENTER AND OFFSHORE AND WINDS HAVE STEADILY
DECREASED BELOW TROPICAL STORM FORCE...EVEN AT THE ELEVATED OIL
PLATFORMS OVER THE NORTHERN GULF OF MEXICO. THEREFORE THE INITIAL
INTENSITY HAS BEEN REDUCED TO 30 KT...WITH THESE WINDS FOUND ONLY
WELL SOUTH AND EAST OF THE CENTER OVER WATER.  

LEE IS ALREADY BEGINNING TO LOSE TROPICAL CHARACTERISTICS WITH
WARM/COASTAL FRONTOGENESIS UNDERWAY EAST OF THE CENTER AND THE
SURFACE CENTER BECOMING ELONGATED FROM SOUTHWEST TO NORTHEAST IN
THE PRESSURE AND WIND FIELDS. AS THE CYCLONE BEGINS TO INTERACT
WITH AN UNUSUALLY STRONG MID/UPPER-LEVEL TROUGH DIGGING INTO THE
MISSISSIPPI VALLEY...LEE SHOULD BE EXTRATROPICAL BY 24 HOURS WHEN
GLOBAL MODELS SHOW THE LOW EMBEDDED IN A LOW-LEVEL BAROCLINIC ZONE
AND THE CIRCULATION MERGING WITH A MID-LATITUDE SHORTWAVE TROUGH.
AS THIS TRANSITION OCCURS...THE GFS AND ECMWF MODELS SHOW A 6-12
HOUR PERIOD OF GALE-FORCE WINDS OVER THE GULF WATERS SOUTHEAST OF
THE CENTER...AND THIS IS INDICATED IN THE OFFICIAL FORECAST. THIS
HAZARD WILL BE HANDLED BY MARINE PRODUCTS FROM LOCAL NATIONAL
WEATHER SERVICE OFFICES AND THE NATIONAL HURRICANE CENTER. AFTER
EXTRATROPICAL TRANSITION...THE CYCLONE SHOULD SLOWLY WEAKEN AND
DISSIPATE BY 72 HOURS. 

LEE HAS MADE ITS TURN TOWARD THE EAST-NORTHEAST...WITH AN INITIAL
MOTION ESTIMATE OF 060/06. AS THE THE SHORTWAVE TROUGH CUTS OFF
INTO A CLOSED LOW OVER THE TENNESSEE VALLEY...LEE WILL TURN TOWARD
THE NORTHEAST AND THEN THE NORTH-NORTHEAST OVER THE NEXT 48 HOURS
AS IT IS ABSORBED INTO THE CIRCULATION OF THE CUTOFF. THE NEW TRACK
FORECAST IS A LITTLE TO THE LEFT OF AND FASTER THAN THE PREVIOUS
ONE...SHOWING A SHARPER TURN BACK TOWARD THE NORTH...AND IS CLOSE
TO A BLEND OF THE GFS AND ECMWF.   

THE MAIN HAZARD FROM LEE AND ITS REMNANTS WILL BE VERY HEAVY
RAINFALL SPREADING FROM THE CENTRAL GULF COAST STATES INTO THE
TENNESSEE VALLEY AND SOUTHERN APPALACHIANS IN THE NEXT FEW DAYS.
PLEASE SEE PRODUCTS FROM YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE
ON THE HEAVY RAINFALL AND FLOODING THREAT. 
 
THIS IS THE LAST NHC ADVISORY ON LEE. FUTURE INFORMATION ON THIS
SYSTEM CAN BE FOUND IN PUBLIC ADVISORIES ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER...UNDER AWIPS HEADER TCPAT3
AND WMO HEADER WTNT33 KWNH...BEGINNING AT 4 AM CDT. FOR MARINE
INTERESTS ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN
HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0300Z 31.0N  91.4W   30 KT  35 MPH
 12H  05/1200Z 31.3N  90.5W   35 KT  40 MPH...POST-TROPICAL
 24H  06/0000Z 32.3N  88.8W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  06/1200Z 33.6N  87.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  07/0000Z 34.8N  86.9W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  08/0000Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 
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