000 WTNT41 KNHC 202046 TCDAT1 Hurricane Oscar Discussion Number 7 NWS National Hurricane Center Miami FL AL162024 500 PM EDT Sun Oct 20 2024 Oscar is very close to making landfall this afternoon along the northern coast of eastern Cuba. Since the final observations from the morning Air Force Reconnaissance mission, the hurricane's structure on satellite imagery and radar out of Guantanamo Bay has not changed appreciably, with rotating cold convective bands noted on 1 minute GOES-16 imagery, and the eyewall on radar coming and going, occasionally open on the western side. Subjective and objective intensity estimates have not changed much from when the plane was in the hurricane this morning, so the initial intensity will remain at 70 kt this advisory. Oscar has continued a west-southwestward motion, but is slowing down as it nears the Cuban coast, estimated now at 250/5 kt. The strongest mid-level ridging is now oriented to the northwest of Oscar and is helping to steer the small hurricane west-southwestward into Cuba. However, by tomorrow a digging shortwave trough on the eastern side of a broader trough across the western Atlantic should further erode the steering flow north of Oscar, with much of the track guidance showing the system executing a slow but sharp turn northward on Monday, ultimately causing the tropical cyclone to emerge back out over open waters in 24-36 h. How fast Oscar then accelerates to the northeast could be related to how vertically deep the circulation is by the early part of this week, with the GFS showing a shallow Oscar drifting slowly over the central Bahamas, while the ECMWF keeps a stronger Oscar accelerating northeastward. The NHC track forecast is a little faster than the previous advisory, slightly favoring the ECMWF forecast solution over the GFS given its better performance with this small tropical cyclone, and lies not far off the TVCA and HCCA consensus aids. The small inner core of Oscar is likely to be severely disrupted by the higher terrain of eastern Cuba after it makes landfall, and weakening after it moves ashore will likely be quick. Some of the guidance, especially the GFS, suggests that Oscar could weaken more than shown here in the latest NHC intensity forecast. Once Oscar re-emerges over the Atlantic Ocean, the forecast environment is not very favorable for reintensification, with westerly shear increasing above 30 kt in 36 h and plenty of very dry air waiting to be imported into the cyclone's core. The NHC forecast does not show any intensification after it emerges back offshore, and most of the guidance shows the small cyclone being absorbed by the much larger baroclinic trough sometime this week, though the timing varies among the global and hurricane-regional model guidance. Key Messages: 1. A Hurricane Warning is in effect for a portion of the northern coast of eastern Cuba where Oscar is expected to make landfall shortly. 2. Oscar is expected to produce a dangerous storm surge on portions of the north shore of eastern Cuba this afternoon and evening. 3. Through midweek, heavy rainfall from Oscar will lead to areas of significant, potentially life-threatening flash flooding along with mudslides across portions of eastern Cuba, especially within the Sierra Maestra. In addition, localized flash flooding will be possible across the southeastern Bahamas. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 20.5N 74.3W 70 KT 80 MPH 12H 21/0600Z 20.4N 75.0W 55 KT 65 MPH...INLAND 24H 21/1800Z 20.6N 75.4W 40 KT 45 MPH...INLAND 36H 22/0600Z 21.6N 75.5W 40 KT 45 MPH...OVER WATER 48H 22/1800Z 22.7N 75.0W 40 KT 45 MPH 60H 23/0600Z 23.7N 73.9W 40 KT 45 MPH 72H 23/1800Z 25.2N 72.0W 35 KT 40 MPH 96H 24/1800Z...DISSIPATED $$ Forecaster Papin