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| #534658 (Received by flhurricane at: 10:35 AM 16.Aug.2012) TCDAT3 TROPICAL STORM GORDON DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012 1100 AM AST THU AUG 16 2012 VISIBLE SATELLITE IMAGERY INDICATES TIGHTLY CURVED CONVECTIVE BANDS HAVE FORMED AROUND A SMALL CENTRAL DENSE OVERCAST...WHICH INDICATES THAT GORDON IS STRENGTHENING. SATELLITE INTENSITY ESTIMATES ARE T3.0 FROM TAFB...T2.5 FROM SAB...AND T2.7 ADT FROM UW-CIMSS. GIVEN THE MID-LEVEL BANDED EYE FEATURE NOTED IN A 16/1143 UTC SSMIS MICROWAVE IMAGE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 45 KT...WHICH IS SUPPORTED BY THE 45-KT TAFB INTENSITY ESTIMATE. GORDON IS RECURVING TO THE NORTHEAST...AND THE INITIAL MOTION IS NOW 045/14 KT. THE CYCLONE HAS ROUNDED THE SUBTROPICAL RIDGE AXIS AND WILL BE MOVING INTO THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-24 HOURS. AS A RESULT...GORDON SHOULD GRADUALLY TURN TOWARD THE EAST THROUGH 72 HOURS. AFTER THAT TIME...THE CYCLONE IS EXPECTED TO LIFT OUT TOWARD THE NORTHEAST AHEAD OF A DIGGING SHORTWAVE TROUGH AND BE NEAR THE AZORES ISLANDS IN ABOUT 4 DAYS. THE NHC MODEL GUIDANCE IS TIGHTLY PACKED AROUND THE PREVIOUS FORECAST TRACK... SO ONLY MINOR TWEAKS WERE MADE FOR THIS ADVISORY. SATELLITE IMAGERY INDICATES THAT UPPER-LEVEL OUTFLOW HAS BECOME WELL ESTABLISHED IN ALL QUADRANTS...ESPECIALLY IN THE NORTHEASTERN SEMICIRCLE. THE VERTICAL SHEAR IS FORECAST TO REMAIN FAVORABLE FOR ABOUT THE NEXT 36 HOURS AND WARM SEA-SURFACE TEMPERATURES OF AT LEAST 27C LIE AHEAD OF THE CYCLONE. AS A RESULT OF THESE FAVORABLE CONDITIONS...STEADY INTENSIFICATION SEEMS REASONABLE ALTHOUGH DRY MID-LEVEL AIR IS BEGINNING TO ENCROACH FROM THE WEST. BY 48 HOURS...WESTERLY WIND SHEAR AND DRY AIR ENTRAINMENT ARE EXPECTED TO SHARPLY INCREASE...WHICH SHOULD ACT TO PUT A BRAKE ON THE STRENGTHENING PROCESS. AS GORDON APPROACHES THE AZORES IN 4 DAYS... THE SYSTEM COULD MERGE WITH A FRONTAL SYSTEM AND TRANSITION INTO A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS IDENTICAL TO THE PREVIOUS ADVISORY...AND IS CLOSE TO INTENSITY CONSENSUS MODEL...IV15. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 33.3N 53.8W 45 KT 50 MPH 12H 17/0000Z 34.3N 51.8W 50 KT 60 MPH 24H 17/1200Z 34.9N 48.3W 55 KT 65 MPH 36H 18/0000Z 34.9N 44.5W 60 KT 70 MPH 48H 18/1200Z 34.8N 40.6W 65 KT 75 MPH 72H 19/1200Z 35.6N 32.7W 60 KT 70 MPH 96H 20/1200Z 37.9N 25.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 21/1200Z 40.4N 19.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART |
