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TROPICAL STORM FLORENCE DISCUSSION NUMBER   5
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT TUE SEP 12 2000
 
THERE WAS AN ENTRAINMENT OF DRY MID-TROPOSPHERIC AIR INTO THE
CIRCULATION...WHICH DIMINISHED THE DEEP CONVECTION.  HOWEVER RECENT
WATER VAPOR IMAGES SUGGEST THAT THIS INFLUENCE MAY BE ABATING...
WITH AN INCREASE IN THE CENTRAL CONVECTION...ALONG WITH AN EYE-LIKE
WARM SPOT.  EVEN THOUGH THE SYSTEMS LACKS THE CLASSIC ANTICYCLONIC
UPPER-TROPOSPHERIC OUTFLOW PATTERN...VERTICAL SHEAR HAS BECOME
RELATIVELY WEAK AND IT IS SITUATED OVER 28 DEG C SST.  THEREFORE
STRENGTHENING TO A HURRICANE IS LIKELY...IF FLORENCE IS NOT ONE
ALREADY.  AIR FORCE RECON IS SCHEDULED FOR 12Z AND THIS WILL GIVE A
BETTER GAUGE OF INTENSITY.
 
THERE HAS BEEN LITTLE MOTION OVERNIGHT AS THE TROPICAL CYCLONE IS
ESSENTIALLY WEDGED IN BETWEEN TWO MID-TROPOSPHERIC ANTICYCLONES TO
THE NORTHWEST AND SOUTHEAST.  STEERING CURRENTS ARE LIKELY TO REMAIN
WEAK FOR A WHILE AND TRACK GUIDANCE MODELS SHOW LITTLE MOVEMENT FOR
THE NEXT COUPLE OF DAYS.  THEREAFTER...THE GLOBAL MODELS SHOW AN
AMPLIFYING 500 MB TROUGH ALONG THE U.S. EAST COAST...CREATING AN
INCREASING WESTERLY TO SOUTHWESTERLY STEERING FLOW FOR FLORENCE.
THUS...WE EXPECT ERRATIC MOTION...OR A VERY SLIGHT WESTWARD
DISPLACEMENT...DURING THE NEXT DAY OR TWO FOLLOWED BY AN EAST-
NORTHEASTWARD MOTION IN THE LATTER PART OF THE FORECAST PERIOD.  THE
CURRENT OFFICIAL TRACK FORECAST IS FAIRLY SIMILAR TO THE PREVIOUS
ONE AND IS ALSO CLOSE TO THE LATEST GFDL AND U.K. MET. OFFICE
GUIDANCE.
 
FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/0900Z 30.2N  72.8W    60 KTS
12HR VT     12/1800Z 30.3N  73.3W    65 KTS
24HR VT     13/0600Z 30.4N  74.0W    70 KTS
36HR VT     13/1800Z 30.5N  73.5W    70 KTS
48HR VT     14/0600Z 30.5N  73.0W    70 KTS
72HR VT     15/0600Z 31.5N  70.5W    70 KTS
 
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