|
Show Selection: |
| #6348 (Received by flhurricane at: 4:44 PM 28.Aug.2004) TCDAT2 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 |
