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| #6305 (Received by flhurricane at: 10:48 AM 28.Aug.2004) TCDAT2 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 |
