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Tropical Storm Ophelia Forecast Discussion Number 10
2017-10-11 16:40:05| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Wed Oct 11 2017 000 WTNT42 KNHC 111439 TCDAT2 Tropical Storm Ophelia Discussion Number 10 NWS National Hurricane Center Miami FL AL172017 1100 AM AST Wed Oct 11 2017 If I only had conventional satellite imagery, I would definitely estimate that Ophelia was a hurricane. The cyclone has a ragged eye surrounded by deep convection and cyclonically curved bands. Furthermore, Dvorak intensity estimates, both subjective and objective, from all agencies are T4.0 plus. However, several ASCAT passes during the past day or so indicate that the winds have been lower than the winds one could assign the cyclone by using Dvorak. Once again this morning, a pair of ASCAT passes showed winds of less than 45 kt, but I am assuming that the ASCAT can not resolve the sharp wind gradient typically associated with an eyewall, and earlier SSMIS data indicated that one is present. Since we do not have a hurricane hunter plane to give us exact measurements, we need to compromise between the very valuable satellite-based estimates, and the initial intensity is set at 60 kt in this advisory. Although the ocean is not too warm, the shear is low and the upper-troposphere is cool. These factors should provide some low-octane fuel favoring slight strengthening, and Ophelia is still expected to become a hurricane at any time within the next 12 hours. Extratropical transition is likely to start between day 3 and day 4, and Ophelia is anticipated to remain a strong cyclone over the northeastern Atlantic. Ophelia is moving slowly toward the east at 3 kt, embedded within light steering currents, and little motion is expected today. A mid-level trough is forecast to amplify west of Ophelia, and this pattern will provide a stronger southwesterly steering flow which eventually force the cyclone to move toward the northeast with increasing forward speed. Most of the track models agree with this solution increasing the confidence in the track forecast. The NHC forecast follows very closely the HFIP corrected consensus HCCA which has been very skillful this season. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 30.0N 36.5W 60 KT 70 MPH 12H 12/0000Z 29.9N 36.0W 65 KT 75 MPH 24H 12/1200Z 30.1N 35.7W 70 KT 80 MPH 36H 13/0000Z 30.8N 34.7W 70 KT 80 MPH 48H 13/1200Z 31.5N 33.3W 70 KT 80 MPH 72H 14/1200Z 34.0N 26.8W 70 KT 80 MPH 96H 15/1200Z 40.0N 17.5W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 16/1200Z 51.5N 12.5W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Avila
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