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Tropical Storm FLOSSIE (Text)

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TROPICAL STORM FLOSSIE DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092007
800 AM PDT THU AUG 09 2007
 
ALTHOUGH THE AMOUNT OF DEEP CONVECTION WITH FLOSSIE HAS DECREASED
SOMEWHAT OVER THE PAST COUPLE OF HOURS...THE CYCLONE IS MAINTAINING
WELL-DEFINED CONVECTIVE BANDS IN THE NORTHERN SEMICIRCLE AND A
SEPARATE AREA OF DEEP CONVECTION JUST SOUTH OF THE PRESUMED CENTER. 
GOOD OUTFLOW IS EVIDENT IN ALL QUADRANTS EXCEPT THE EAST.  DVORAK
INTENSITY ESTIMATES FROM TAFB AND SAB WERE 45 KT...AND THE ADVISORY
INTENSITY WILL REMAIN 45 KT. 

FLOSSIE IS EXPECTED TO REMAIN OVER 27C-PLUS WATERS FOR ABOUT 48
HOURS.  GIVEN THE PRESENT BANDING STRUCTURE AND GOOD OUTFLOW...
FURTHER DEVELOPMENT IS EXPECTED.  THE SHIPS...HWRF...AND GFDL
MODELS ALL FORECAST FLOSSIE TO BECOME A HURRICANE.  AFTER 48
HOURS...SSTS ALONG THE FORECAST TRACK DECREASE BUT NOT
RAPIDLY...AND THE GFS SUGGESTS THAT A FAVORABLE UPPER-LEVEL PATTERN
COULD PERSIST EVEN AFTER SSTS BEGIN TO COOL.  THIS ARGUES FOR A
RELATIVE SLOW WEAKENING TREND DURING DAYS 3-5.

THE INITIAL MOTION REMAINS 265/12.  FLOSSIE IS NEAR THE SOUTHWESTERN
EDGE OF A MID-LEVEL RIDGE...BUT GLOBAL MODELS SUGGEST THAT ENOUGH
RIDGING WILL BUILD WESTWARD TO KEEP THE CYCLONE FROM INTERACTING
MUCH WITH A MID- TO UPPER-LEVEL TROUGH CURRENTLY NEAR 135W.  MODEL
GUIDANCE OFFERS TWO BASIC SCENARIOS.  THE GFDL...HWRF...AND GFS
MAINTAIN A RELATIVELY STRONG SYSTEM ON A WEST-NORTHWESTERLY
TRACK...WHILE THE UKMET...ECMWF...AND NOGAPS WEAKEN THE CYCLONE IN
A DAY OR TWO AND TAKE IT MORE RAPIDLY WESTWARD IN THE LOW-LEVEL
FLOW.  ASSUMING FLOSSIE DEVELOPS AS EXPECTED...THE FORMER SCENARIO
SEEMS MORE REASONABLE.  THE OFFICIAL FORECAST IS VERY SIMILAR TO
THE PREVIOUS ADVISORY AND CLOSE TO A BLEND OF THE GFS...GFDL...AND
HWRF MODELS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/1500Z 13.0N 130.9W    45 KT
 12HR VT     10/0000Z 12.9N 132.7W    50 KT
 24HR VT     10/1200Z 13.1N 135.0W    60 KT
 36HR VT     11/0000Z 13.3N 137.0W    65 KT
 48HR VT     11/1200Z 13.5N 139.0W    65 KT
 72HR VT     12/1200Z 14.0N 143.0W    55 KT
 96HR VT     13/1200Z 15.0N 147.5W    50 KT
120HR VT     14/1200Z 16.0N 151.5W    45 KT
 
$$
FORECASTER FRANKLIN
 
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