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#906749 (Received by flhurricane at: 4:49 AM 12.Oct.2017) TCDAT2 Hurricane Ophelia Discussion Number 13 NWS National Hurricane Center Miami FL AL172017 500 AM AST Thu Oct 12 2017 Satellite imagery indicates that Ophelia continues to gradually become better organized, with the hurricane maintaining a well-defined eye and the cloud tops in the eyewall gradually cooling. The various subjective and objective satellite intensity estimates range between 75-90 kt, and based on the previous trend of the intensity being near the lower end of the estimates, the initial intensity is kept at a possibly conservative 75 kt. The initial motion is 040/3. Ophelia is currently in an area of light steering currents to the south of the mid-latitude westerlies. The large-scale models forecast a deep-layer trough to amplify over the central and northeastern Atlantic during the forecast period, which should steer Ophelia northeastward or east-northeastward at an increasing forward speed for the next few days. The track guidance has changed little since the last advisory, and the new forecast track, which leans toward the HFIP Corrected Consensus and the Florida State Superensemble, is an update of the previous forecast. Ophelia is forecast to remain in a light to moderate shear environment and over marginal sea surface temperatures for the next 24-36 h, and the intensity forecast shows some strengthening during this time in agreement with the guidance. After that, the hurricane is expected to move over cooler water. As that happens, though, interaction with the above-mentioned westerly trough should help Ophelia keep its intensity. Extratropical transition should begin by 72 h, with Ophelia likely to become a hurricane-force baroclinic low by 96 h. The guidance is in good agreement that Ophelia should affect Ireland, northern Ireland and Great Britain between 96-120 h as a powerful extratropical low. Although the track guidance keeps the center offshore of the Azores, a tropical storm watch or warning could be needed for the eastern Azores on Thursday because of the forecasted increase in wind radii in the northwestern quadrant of the cyclone. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 30.3N 35.6W 75 KT 85 MPH 12H 12/1800Z 30.7N 35.2W 80 KT 90 MPH 24H 13/0600Z 31.3N 34.0W 80 KT 90 MPH 36H 13/1800Z 32.2N 32.0W 75 KT 85 MPH 48H 14/0600Z 33.7N 28.6W 75 KT 85 MPH 72H 15/0600Z 38.5N 20.5W 75 KT 85 MPH 96H 16/0600Z 49.0N 13.5W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 17/0600Z 59.0N 7.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven |