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#936325 (Received by flhurricane at: 11:08 AM 16.Aug.2018) TCDAT5 Subtropical Storm Ernesto Discussion Number 6 NWS National Hurricane Center Miami FL AL052018 1100 AM AST Thu Aug 16 2018 Convection developed closer to the center of Ernesto early this morning, suggesting that the system was attempting to make the transition to a tropical cyclone, but that area of convection has weakened within the past couple of hours. Patches of deep convection continue over the outer portion of the circulation, and a very recent ASCAT overpass continues to show a rather large radius of maximum winds, indicating that Ernesto remains a subtropical cyclone. The ASCAT data showed a large area of 35-40 kt winds over the eastern and southeastern portions of the circulation, so the initial wind speed has been increased to 40 kt. Ernesto has likely reached its peak intensity since it will be moving over much cooler SSTs later today, and the cyclone is expected to lose its subtropical characteristics late tonight or early Friday. The post-tropical cyclone should be able to maintain its intensity due in part to its expected fast forward speed over the North Atlantic. The global models indicate that the system will merge with a frontal zone as it approaches Ireland and the United Kingdom late Saturday. Ernesto has turned northeastward and is beginning to accelerate, and is now moving at around 14 kt. The cyclone should be fully embedded within the mid-latitude westerlies within the next 24 hours, and a significantly faster northeastward to east-northeastward motion is expected over the next couple of days. The track guidance continues to be in good agreement, and the new NHC official forecast is essentially an update of the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 42.0N 43.2W 40 KT 45 MPH 12H 17/0000Z 43.9N 40.4W 40 KT 45 MPH 24H 17/1200Z 46.7N 35.0W 40 KT 45 MPH...POST-TROPICAL 36H 18/0000Z 49.5N 28.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 18/1200Z 52.0N 19.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 19/1200Z...DISSIPATED $$ Forecaster Brown |