Tropical Storm GASTON

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TROPICAL STORM GASTON DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SAT AUG 28 2004
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
THAT GASTON IS STRONGER THAN PREVIOUSLY THOUGHT.  THE AIRCRAFT
MEASURED 59 KT WINDS AT 1500 FT FLIGHT LEVEL TO THE NORTH OF THE
CENTER AND MEASURED A CENTRAL PRESSURE OF 996 MB.  THE LOW-LEVEL
CENTER...WHICH WAS EXPOSED EARLIER...IS NOW COVERED BY A NEW BURST
OF CONVECTION...AND THE CHARLESTON WSR-88D SHOWS A GOOD CURVED BAND
PATTERN.  SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM SAB AND
AFWA...AND 45 KT FROM TAFB.  THE INITIAL INTENSITY IS SET AT 45
KT...AND THIS MAY BE A LITTLE CONSERVATIVE.

THE INITIAL MOTION REMAINS A WESTWARD DRIFT...270/3.  STEERING
CURRENTS ARE CURRENTLY WEAK.  HOWEVER...SATELLITE IMAGERY SHOWS A
RIDGE BUILDING OVER THE ATLANTIC NORTHEAST OF THE STORM...AND
LARGE-SCALE MODELS SHOW A DEEP-LAYER TROUGH MOVING EASTWARD INTO
THE EASTERN AFTER 24 HR.  THIS COMBINATION SHOULD ALLOW FOR A SLOW
NORTHWESTWARD TO NORTHWARD 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 LEFT AND A
LITTLE FASTER THAN THE PREVIOUS FORECAST DURING THE FIRST 48 HR.
 
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 60 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.  THERE IS A POSSIBILITY THAT GASTON
COULD REACH HURRICANE STRENGTH AS IT APPROACHES THE SOUTH CAROLINA
COAST ON SUNDAY...AND THIS REQUIRES A HURRICANE WATCH FOR THE SOUTH
CAROLINA COAST.

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      28/2100Z 31.4N  78.9W    45 KT
 12HR VT     29/0600Z 31.8N  79.4W    55 KT
 24HR VT     29/1800Z 32.7N  79.7W    60 KT
 36HR VT     30/0600Z 33.7N  79.6W    50 KT...INLAND
 48HR VT     30/1800Z 34.9N  78.4W    40 KT...INLAND
 72HR VT     31/1800Z 37.5N  74.0W    35 KT...OVER WATER
 96HR VT     01/1800Z 41.0N  66.5W    30 KT...EXTRATROPICAL
120HR VT     02/1800Z 43.0N  55.0W    30 KT...EXTRATROPICAL
 
 
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