Tropical Storm GASTON

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TROPICAL STORM GASTON DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT AUG 28 2004

MORNING VISIBLE SATELLITE IMAGERY SHOWS THAT TROPICAL DEPRESSION
SEVEN HAS SIGNIFICANTLY INCREASED IN ORGANIZATION...WITH A CURVED
CONVECTIVE BAND WRAPPED HALFWAY AROUND THE CENTER.  SATELLITE
INTENSITY ESTIMATES ARE 45 KT FROM SAB AND 35 KT FROM TAFB.  THE
DEPRESSION IS THUS UPGRADED TO TROPICAL STORM GASTON WITH 35 KT
WINDS.  AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED
TO INVESTIGATE THE SYSTEM THIS AFTERNOON.

THE INITIAL MOTION IS A WESTWARD DRIFT...270/2.  STEERING CURRENTS
ARE CURRENT WEAK.  HOWEVER...LARGE-SCALE MODELS SUGGEST THAT A
RIDGE WILL BUILD OVER THE ATLANTIC NORTHEAST OF THE STORM...
FOLLOWED BY A DEEP-LAYER TROUGH MOVING EASTWARD INTO THE EASTERN
UNITED STATES.  THIS COMBINATION SHOULD ALLOW FOR A SLOW
WEST-NORTHWESTWARD MOTION...FOLLOWED IN ABOUT 36-48 HR BY
RECURVATURE TO THE NORTHEAST AND THEN ACCELERATION.  GUIDANCE
GENERALLY AGREES WITH THE DIRECTION...ALTHOUGH THERE IS SOME SPREAD
ON THE SPEED.  THE FORECAST TRACK IS A LITTLE TO THE RIGHT AND A
LITTLE FASTER THAN THE PREVIOUS FORECAST DURING THE FIRST 48 HR...
AND THEN SOMEWHAT SLOWER THEREAFTER.
 
AN UPPER-LEVEL RIDGE IS OVER GASTON AT THIS TIME...AND THE SHEAR IS
LIGHT.  THUS...STEADY STRENGTHENING IS EXPECTED UNTIL LANDFALL...
WITH THE LANDFALL INTENSITY OF 50 KT BEING A COMPROMISE BETWEEN THE
STRONGER SHIPS AND THE WEAKER GFDL.  GASTON SHOULD WEAKEN AFTER
LANDFALL...THEN BECOME EXTRATROPICAL OVER THE ATLANTIC TO THE EAST
OF THE MID-ATLANTIC STATES.
 
THE FORECAST TRACK AND WIND RADII REQUIRE TROPICAL STORM WARNINGS
FOR THE SOUTH CAROLINA COAST AT THIS TIME.  DUE TO THE RELATIVELY
SLOW MOTION DURING THE FIRST 48 HR...THERE IS A POTENTIAL FOR HEAVY
RAINS ALONG THE TRACK OF GASTON.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/1500Z 31.4N  78.5W    35 KT
 12HR VT     29/0000Z 31.5N  78.9W    40 KT
 24HR VT     29/1200Z 32.1N  79.5W    45 KT
 36HR VT     30/0000Z 32.8N  79.8W    50 KT...INLAND
 48HR VT     30/1200Z 33.9N  79.2W    40 KT...INLAND
 72HR VT     31/1200Z 36.0N  76.0W    35 KT...INLAND
 96HR VT     01/1200Z 40.0N  68.5W    30 KT...OVER WATER
120HR VT     02/1200Z 42.5N  59.0W    30 KT...EXTRATROPICAL
 
 
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