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Hurricane Ophelia Forecast Discussion Number 27
2017-10-15 22:42:43| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sun Oct 15 2017 000 WTNT42 KNHC 152042 TCDAT2 Hurricane Ophelia Discussion Number 27 NWS National Hurricane Center Miami FL AL172017 500 PM AST Sun Oct 15 2017 Ophelia's cloud structure is declining rapidly, and microwave and shortwave IR imagery indicate that the low-level and mid-level centers are becoming separated. However, some deep convection is still present near Ophelia's center, and an SSMIS pass from 1827 UTC indicated that the hurricane still has an inner core that is separated from a front to the north and west. The estimated maximum winds have been decreased slightly to 75 kt given the overall decay of the cloud structure. However, the cyclone's favorable position relative to an upper-level jet streak is likely contributing to deepening of the low as the wind field expands substantially. Only a slight decrease in the maximum winds is therefore expected before the post-tropical cyclone reaches Ireland. After that time, interaction with land while the cyclone occludes should cause it to weaken more rapidly. Around 48 h, the cyclone's circulation is likely to become ill-defined and dissipate near the western coast of Scandinavia. Ophelia has continued to move toward the north-northeast, and the initial motion estimate remains 025/33 kt. There has been no change to the track forecast reasoning since Ophelia is already embedded within the flow associated with a large mid-latitude trough. This should keep Ophelia on a north-northeast heading as it passes over Ireland and the UK on Monday. The dynamical guidance remains in very good agreement on the track of Ophelia, and very little change has been made to the track forecast. Since Ophelia will be post-tropical as it approaches Ireland and the UK, strong winds and rain will arrive over land areas sooner than the center. For more information on local impacts, consult products from local meteorological services in Ireland and the United Kingdom for more information. KEY MESSAGES: 1. Ophelia is expected to be a powerful extratropical cyclone with hurricane force winds while it moves near Ireland and the United Kingdom. Direct impacts from wind and heavy rain in portions of these areas are likely, along with dangerous marine conditions. For more details on the magnitude, timing, and location of impacts from post-tropical Ophelia, residents in Ireland should refer to products issued by Met Eireann, and residents in the United Kingdom should refer to products issued by the Met Office. 2. Individuals are urged to not focus on the exact track of Ophelia since strong winds and heavy rainfall will extend well outside of the NHC forecast cone. FORECAST POSITIONS AND MAX WINDS INIT 15/2100Z 44.6N 13.3W 75 KT 85 MPH 12H 16/0600Z 49.2N 11.3W 70 KT 80 MPH...POST-TROP/EXTRATROP 24H 16/1800Z 54.3N 7.5W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 17/0600Z 58.5N 2.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 17/1800Z...DISSIPATED $$ Forecaster Zelinsky
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