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TROPICAL STORM FLOYD DISCUSSION NUMBER  10
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU SEP 09 1999
 
DESPITE THE APPARENT FAVORABLE CONDITIONS FOR STRENGTHENING...FLOYD
HAS NOT REACHED HURRICANE STATUS YET.  YES...ON IR IMAGERY...FLOYD
IS VERY IMPRESSIVE WITH EXCELLENT OUTFLOW...VERY DEEP CONVECTION AND
BANDING FEATURES.  IN FACT...T-NUMBERS FROM SAB...TAFB AND KGWC ARE
4.0 ON THE DVORAK SCALE...SUGGESTING THAT FLOYD IS A HURRICANE. 
HOWEVER... SEVERAL PASSES THROUGH THE CENTER OF FLOYD BY AN AIR
FORCE RECONNAISSANCE PLANE INDICATE THAT THE LOW-LEVEL CENTER IS
DECOUPLED FROM THE MID-LEVEL ROTATION OBSERVED IN IR IMAGERY. 
NEITHER THE PRESSURE NOR THE WINDS REPORTED SO FAR BY THE
PLANE...CONFIRM THAT FLOYD IS A HURRICANE. I DO NOT HAVE AN
EXPLANATION WHY STRENGTHENING HAS NOT MATERIALIZED YET...BUT I AM
SURE THERE WILL BE MANY EXPLANATIONS OUT THERE LATER.  GIVEN THE
CURRENT SEPARATION OF THE LOW AND MID LEVEL CENTERS...NO SIGNIFICANT
STRENGTHENING IS LIKELY DURING THE NEXT 6 TO 12 HOURS. 
THEREAFTER...INTENSIFICATION SHOULD BEGIN AS INDICATED BY SHIPS AND
THE GFDL MODELS AND PREVIOUS FORECAST.

FLOYD HAS SLOWED DOWN A LITTLE BIT AND THE INITIAL MOTION IS 285/9. 
THE TRACK IN THE SHORT TERM...WILL PROBABLY BE CONTROLLED BY A WELL
DEFINED UPPER-LEVEL TROUGH/SHEAR AXIS EXTENDING FROM HISPANIOLA
NORTHWARD THROUGH THE ATLANTIC AS OBSERVED IN WATER VAPOR IMAGERY.
THIS TROUGH MAY FORCE FLOYD ON A TRACK MORE TO THE WEST-NORTHWEST
AND EVEN NORTHWEST DURING THE NEXT 24 TO 36 HOURS.  THEREAFTER...THE
STEERING PATTERN BECOMES MORE COMPLICATED BECAUSE GLOBAL MODELS ARE
BEGINNING TO HINT THAT A HIGH PRESSURE RIDGE WILL BUILD OVER THE
WESTERN ATLANTIC.  THIS FORECAST PATTERN WOULD FAVOR A MORE WEST OR
WEST-NORTHWESTERLY TRACK INSTEAD OF A NORTHWARD TURN OVER OPEN
WATERS.  THIS IS BASED ON SEVERAL RELIABLE MODELS LIKE
LBAR...GFDL...AND THE AVN WHICH TURN FLOYD WESTWARD BY THE END OF
THE FORECAST PERIOD.  IN ADDITION...THE UK MODEL SUGGESTS A 
NORTHWARD TURN FARTHER TO THE WEST IN EACH UPDATED RUN.  SINCE
MODELS COULD CHANGE AGAIN TO A MORE NORTHERLY TRACK IN THE NEXT
RUN....THE OFFICIAL FORECAST IS NOT CHANGED AND CONTINUES ON A
GENERAL WEST-NORTHWEST TRACK...MOVING FLOYD NORTH OF THE LEEWARD
ISLANDS AND THEN BENDS THE TRACK A LITTLE TO THE WEST BEYOND 48
HOURS.

AVILA 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL     10/0300Z 18.3N  57.7W    60 KTS
12HR VT     10/1200Z 18.7N  59.1W    60 KTS
24HR VT     11/0000Z 20.0N  61.0W    70 KTS
36HR VT     11/1200Z 21.2N  62.7W    80 KTS
48HR VT     12/0000Z 22.5N  64.5W    90 KTS
72HR VT     13/0000Z 23.5N  68.5W   100 KTS
 
 
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