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| #534737 (Received by flhurricane at: 4:41 PM 16.Aug.2012) TCDAT3 TROPICAL STORM GORDON DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012 500 PM AST THU AUG 16 2012 GORDON HAS BEEN STRENGTHENING OVER THE PAST 12 HOURS. VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW TIGHTLY COILED CONVECTIVE CLOUD BANDS SPIRALING INTO A SMALL CENTRAL DENSE OVERCAST FEATURE. SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T3.0/45 KT FROM SAB...AND T2.7/39 KT ADT FROM UW-CIMSS. AN 1143 UTC SSMIS IMAGE INDICATED A CLOSED MID-LEVEL EYE FEATURE AND A 1311 UTC ASCAT OVERPASS REVEALED 39-KT SURFACE WINDS...WHICH WHEN ADJUSTED FOR THE KNOWN LOW BIAS OF THE SCATTEROMETER DATA YIELDS ABOUT 44 KT. GIVEN THE MUCH IMPROVED BANDING STRUCTURE SINCE THOSE MICROWAVE DATA WERE ACQUIRED...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT. GORDON IS NOW MOVING TOWARD THE EAST-NORTHEAST...OR 055/15 KT...AND IS ON THE PREVIOUS FORECAST TRACK. THE CYCLONE IS MOVING ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE AND WILL BE MOVING INTO THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-18 HOURS. GORDON SHOULD GRADUALLY TURN EASTWARD AND CONTINUE THAT MOTION THROUGH AT LEAST THE 48-HOUR FORECAST PERIOD. BY 72 HOURS...THE CYCLONE IS FORECAST TO BEGIN LIFTING OUT TOWARD THE NORTHEAST AHEAD OF A SHORTWAVE TROUGH...AND BE NEAR THE AZORES ISLANDS BETWEEN DAYS 3 AND 4. THE NHC TRACK GUIDANCE REMAINS TIGHTLY PACKED AROUND THE PREVIOUS FORECAST TRACK...SO NO SIGNIFICANT CHANGES WERE MADE TO THIS FORECAST PACKAGE. UPPER-LEVEL OUTFLOW REMAINS WELL ESTABLISHED IN ALL QUADRANTS...AND DRY MID-LEVEL AIR HAS MANAGED THUS FAR TO REMAIN AWAY FROM THE INNER CORE REGION. WEAK VERTICAL SHEAR COUPLED WITH SSTS GREATER THAN 27C SHOULD ALLOW FOR SOME ADDITIONAL INTENSIFICATION TO OCCUR DURING THE NEXT 24-36 HOURS. BY 48 HOURS...HOWEVER...ENTRAINMENT OF DRY MID-LEVEL AIR FROM THE WEST ALONG WITH INCREASING VERTICAL WIND SHEAR IN EXCESS OF 30 KT SHOULD INDUCE STEADY WEAKENING. AS GORDON NEARS THE AZORES ISLANDS IN 3 TO 4 DAYS...THE CYCLONE IS FORECAST BY MOST OF THE GLOBAL MODELS TO MERGE WITH A FRONTAL SYSTEM AND BECOME A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS ONLY SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY...AND REMAINS CLOSE TO IV15 INTENSITY CONSENSUS MODEL. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 34.2N 52.1W 55 KT 65 MPH 12H 17/0600Z 34.7N 49.9W 60 KT 70 MPH 24H 17/1800Z 34.9N 46.2W 65 KT 75 MPH 36H 18/0600Z 34.7N 42.5W 70 KT 80 MPH 48H 18/1800Z 34.7N 38.6W 60 KT 70 MPH 72H 19/1800Z 36.1N 30.8W 55 KT 65 MPH 96H 20/1800Z 38.8N 23.2W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 21/1800Z 41.2N 15.8W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART |
