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TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT WED SEP 12 2001
 
REPORTS FROM AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT
INDICATE THAT THE TROPICAL DEPRESSION HAS A VERY BROAD CIRCULATION
WITH VERY LIGHT WINDS SURROUNDING THE CENTER.  CONVECTION IS NOT
WELL ORGANIZED WITH RESPECT TO THIS CENTER...BEING ORIENTED IN A
LINEAR BAND THAT EXTENDS FROM NEAR THE YUCATAN PENINSULA TO THE
SOUTHWEST FLORIDA COAST.  HOWEVER...THE UPPER-LEVEL FLOW PATTERN HAS
IMPROVED CONSIDERABLY OVER THE PAST SEVERAL HOURS...AND IS FORECAST
TO REMAIN FAVORABLE OVER THE NEXT DAY OR TWO.  THE WATER IS OF
COURSE QUITE WARM AND THEREFORE STRENGTHENING IS ANTICIPATED.  THE
OFFICIAL FORECAST IS CLOSE TO THE SHIPS GUIDANCE BUT...GIVEN THE
VERY POOR CURRENT ORGANIZATION OF THE SYSTEM...IS MUCH LESS THAN THE
GFDL...WHICH FORECASTS THE SYSTEM TO REACH ABOUT 100 KT BEFORE
LANDFALL.

THE INITIAL MOTION IS 250/2...AND THE RECON POSITION IS A LITTLE
SOUTH OF PREVIOUS ESTIMATES.  STEERING CURRENTS ARE WEAK AND ALL
GUIDANCE INDICATES LITTLE MOTION IN THE SHORT TERM.  NEAR THE END OF
THE FORECAST PERIOD...THE EVOLUTION BECOMES COMPLICATED BY A SHARP
MID-LEVEL SHORT-WAVE TROUGH FORECAST BY THE AVN TO DIG SOUTHEASTWARD
FROM THE OHIO VALLEY...AND IT APPEARS THAT THE LOCATION OF THE
CYCLONE IN THE GULF AT THAT TIME WILL BE CRUCIAL TO ITS ULTIMATE
TRACK.  IN THE AVN...THE CYCLONE IS IN THE NORTHERN GULF...WHERE IT
INTERACTS WITH THE TROUGH AND GETS DRAGGED EASTWARD ACROSS THE
FLORIDA PENINSULA.  MEANWHILE...THE TROUGH TRIGGERS A SEPARATE
BAROCLINIC DEVELOPMENT JUST NORTHEAST OF THE TROPICAL CYCLONE OFF
THE GEORGIA-SOUTH CAROLINA COAST.  THE UKMET HAS A VERY SIMILAR
LARGE SCALE FLOW EVOLUTION...HOWEVER...THE MODEL CYCLONE DRIFTS
WESTWARD IN THE GULF DURING THE FIRST 48 H...WHERE IT IS NOT IN A
POSITION TO BE PICKED UP BY THE TROUGH.  THIS OPTION IS ALSO FAVORED
BY THE NOGAPS AND ETA MODELS...WHICH WOULD KEEP THE SYSTEM IN THE
GULF FOR SOME TIME.  GIVEN THE SOUTHWARD ADJUSTMENT IN THE INITIAL 
POSITION...AND ESPECIALLY THE SPLIT IN THE GUIDANCE...I HAVE PULLED 
BACK A LITTLE FROM THE PREVIOUS FORECAST TRACK AND SHOW A SLOWER 
RECURVATURE TO THE NORTHEAST.

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/0300Z 25.2N  85.8W    30 KTS
12HR VT     13/1200Z 25.3N  86.1W    35 KTS
24HR VT     14/0000Z 25.6N  86.5W    40 KTS
36HR VT     14/1200Z 26.2N  86.6W    50 KTS
48HR VT     15/0000Z 27.0N  86.0W    60 KTS
72HR VT     16/0000Z 28.5N  84.0W    70 KTS
 
 
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