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Tropical Storm FLORENCE


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TROPICAL STORM FLORENCE DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062006
1100 AM EDT WED SEP 06 2006
 
VISIBLE IMAGERY THIS MORNING SHOWS A WELL-DEFINED LOW-CLOUD SWIRL
WITH SOME THIN CONVECTIVE BANDING DEVELOPING IN THE SOUTHEAST AND
NORTHWEST QUADRANTS.  THE STRONGEST CONVECTION CONTINUES TO BE
LOCATED WELL TO THE NORTHEAST OF THE CENTER.  SHIP MSJZ8 REPORTED
34 KT WINDS ABOUT 250 MILES FROM THE CENTER...BEYOND THE STRONGEST
BAND OF CONVECTION.  DVORAK INTENSITY ESTIMATES WERE 45 KT FROM
TAFB AND AFWA...AND 35 KT FROM SAB.  BASED ON THESE DATA...THE
ADVISORY INTENSITY IS INCREASED TO 45 KT.

THE CIRCULATION NOW APPEARS TO BE MORE CIRCULAR THAN IT WAS LAST
NIGHT...AND I AM PLACING THE OVERALL SYSTEM CENTER ONLY A LITTLE
BIT NORTHWEST OF THE CLOUD SWIRL.  THE INITIAL MOTION IS 290/10. 
THE KEY SYNOPTIC FEATURE IN THE SHORT TERM IS THE UPPER LOW
CENTERED ABOUT 500 MILES NORTHWEST OF FLORENCE.  THIS COULD IMPART
MORE OF A NORTHWARD TRACK OVER THE NEXT DAY OR TWO...AS INDICATED
BY THE GFDL MODEL...BUT THE REMAINING GUIDANCE IS TIGHTLY CLUSTERED
ON A CONTINUED WEST-NORTHWESTWARD MOTION OVER THE NEXT THREE DAYS
AS FLORENCE MOVES TO THE SOUTH OF THE MID-LEVEL SUBTROPICAL RIDGE. 
NEAR THE END OF THE FORECAST PERIOD...FLORENCE IS EXPECTED TO ROUND
THE PERIPHERY OF THE RIDGE IN ADVANCE OF A DEEP-LAYER TROUGH OVER
THE EASTERN UNITED STATES.  AT THE MOMENT...MODEL GUIDANCE IS IN
EXCELLENT AGREEMENT ON A NORTHWARD TURN.

THE INTENSIFICATION OF FLORENCE IS VERY DEPENDENT ON JUST HOW IT
INTERACTS WITH THE UPPER-LOW TO ITS NORTHWEST.  RIGHT NOW THE LOW
IS RESPONSIBLE FOR SOUTHWESTERLY SHEAR AND BROAD-SCALE DESCENT OVER
THE CENTER...WITH THE MORE FAVORABLE DIFLUENT FLOW LOCATED WELL TO
THE NORTHEAST.  THE UPPER-LOW IS FORECAST TO RETROGRADE AND WEAKEN
OVER THE NEXT COUPLE OF DAYS...AND THIS WOULD RESULT IN A MORE
FAVORABLE PATTERN FOR STRENGTHENING.  THE OFFICIAL FORECAST FOLLOWS
THIS SCENARIO WITH SLOW DEVELOPMENT OVER THE NEXT 24 HOURS AND MORE
SIGNIFICANT DEVELOPMENT AFTER THAT.  THE GFDL MODEL IS SLIGHTLY
HIGHER THAN THE OFFICIAL FORECAST AND SHOWS FLORENCE AS A MAJOR
HURRICANE IN 3 TO 4 DAYS. 

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/1500Z 18.3N  50.9W    45 KT
 12HR VT     07/0000Z 19.3N  52.5W    50 KT
 24HR VT     07/1200Z 20.5N  54.5W    55 KT
 36HR VT     08/0000Z 22.0N  57.0W    65 KT
 48HR VT     08/1200Z 23.0N  59.5W    75 KT
 72HR VT     09/1200Z 25.0N  64.0W    85 KT
 96HR VT     10/1200Z 28.0N  67.0W    95 KT
120HR VT     11/1200Z 31.0N  67.0W    95 KT
 
$$
FORECASTER FRANKLIN
 
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