Tropical Storm FLOSSIE

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TROPICAL STORM FLOSSIE DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092007
200 PM PDT THU AUG 09 2007
 
THE ORGANIZATION OF FLOSSIE CONTINUES TO IMPROVE...WITH A FORMATIVE
EYE APPARENT IN MICROWAVE AND CONVENTIONAL SATELLITE IMAGERY.
DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB WERE 55 KT...AND A
QUIKSCAT PASS FROM 14Z THIS MORNING SUGGESTED THAT WINDS WERE CLOSE
TO OR JUST BELOW THE CONCURRENT SATELLITE ESTIMATES.
CONSEQUENTLY... THE ADVISORY INTENSITY IS INCREASED TO 55 KT.

THE INITIAL MOTION IS 265/13...ABOUT THE SAME AS BEFORE.  FLOSSIE
WILL BE MOVING TO THE SOUTH OF A WEAKNESS IN THE SUBTROPICAL RIDGE
OVER THE NEXT DAY OR TWO...WHICH COULD SLOW THE FORWARD MOTION A
BIT...BUT THE SMALL CIRCULATION OF FLOSSIE IS UNLIKELY TO INTERACT
SIGNIFICANTLY WITH THIS WEAKNESS.  AFTER THAT...A NARROW MID-LEVEL
RIDGE IS EXPECTED TO KEEP THE CYCLONE ON A WEST OR WEST-NORTHWEST
TRACK THROUGH THE FORECAST PERIOD.  MODEL GUIDANCE IS LARGELY
UNCHANGED FROM THIS MORNING...EXCEPT FOR THE UKMET WHICH HAS
SHIFTED NORTH AND IS NOW CLOSE TO THE HWRF...GFDL...AND GFS.  THE
OFFICIAL FORECAST FOLLOWS A BLEND OF THESE MODELS.  AN ALTERNATIVE
TRACK...FASTER AND FARTHER SOUTH...IS OFFERED BY THE
NOGAPS...ECMWF...AND FSSE.

IN THE SHORT TERM...SOME ADDITIONAL INTENSIFICATION SEEMS LIKELY. 
THE OUTFLOW PATTERN IS RESTRICTED TO THE EAST BUT LOOKS GOOD
ELSEWHERE.  SSTS ALONG THE PROJECTED TRACK WILL REMAIN ABOVE 27C
FOR ANOTHER 36 HOURS OR SO.  THE LOW-LEVEL INFLOW PATTERN DOES NOT
SEEM IDEAL...HOWEVER...WITH A STABLE AIR MASS TO THE NORTHWEST OF
THE CYCLONE AND THE MOIST SOUTHERLY FLOW IN THE SOUTHEAST QUADRANT
SEEMINGLY RUNNING AWAY FROM THE CENTER.  MOST...BUT NOT ALL THE
OBJECTIVE GUIDANCE MAKES FLOSSIE A HURRICANE.  AFTER 48
HOURS...COOLER SSTS SHOULD INDUCE A WEAKENING TREND.  HOW FAST
FLOSSIE DECLINES NEAR THE END OF THE FORECAST PERIOD WILL BE
GOVERNED BY THE UPPER FLOW...WHICH IS FORECAST TO EVOLVE VERY
DIFFERENTLY BY THE VARIOUS LARGE-SCALE MODELS.  THE GFS MAINTAINS A
RELATIVELY FAVORABLE UPPER ENVIRONMENT...WHILE THE ECMWF AND UKMET
HAVE MUCH HIGHER SHEAR.  IT'S DIFFICULT TO TELL WHICH SCENARIO WILL
VERIFY...BUT THE OFFICIAL FORECAST AT THIS POINT CONSERVATIVELY
ASSUMES THAT THE UPPER FLOW WILL NOT BECOME VERY HOSTILE. 

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/2100Z 12.8N 132.4W    55 KT
 12HR VT     10/0600Z 12.8N 134.3W    60 KT
 24HR VT     10/1800Z 13.0N 136.3W    65 KT
 36HR VT     11/0600Z 13.3N 138.4W    65 KT
 48HR VT     11/1800Z 13.6N 140.4W    65 KT
 72HR VT     12/1800Z 14.5N 144.5W    55 KT
 96HR VT     13/1800Z 15.5N 149.0W    50 KT
120HR VT     14/1800Z 16.5N 153.0W    45 KT
 
$$
FORECASTER FRANKLIN
 
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