000 WTNT41 KNHC 210245 TCDAT1 Tropical Storm Oscar Discussion Number 8 NWS National Hurricane Center Miami FL AL162024 1100 PM EDT Sun Oct 20 2024 Oscar made landfall around 2150 UTC as a 70-kt hurricane near the city of Baracoa in the Guantanamo province of eastern Cuba. Radar data from Guantanamo Bay shows Oscar has continued to move slowly over eastern Cuba tonight, with heavy rainfall spreading across the region. Oscar's slow motion will enhance the potential for heavy rainfall, life-threatening flash flooding, and mudslides across eastern Cuba, particularly near higher terrain. There has been notable degradation of Oscar's inner core structure in recent radar and satellite images, which suggests weakening is occurring due to ongoing land interaction. The initial intensity is lowered to 60 kt for this advisory. Oscar wobbled slightly southward on its final approach to Cuba, but recent radar data suggest the system has resumed a slow west-southwestward to westward motion. Oscar should remain over eastern Cuba or very near the coast during the next 12-24 h. Thereafter, the flow ahead of a digging shortwave trough over the southwestern Atlantic is forecast to capture Oscar, which should result in a northeastward acceleration through midweek. The track guidance trended faster this cycle, particularly the ECMWF (which has handled Oscar well) and even the GFS with a shallower vortex depiction. The NHC track forecast once again shows a faster forward speed between 36-72 h, generally between the HCCA/TVCN consensus aids and the GFS/ECMWF (GFEX). Weakening is expected to continue as the inner core structure of Oscar is disrupted by the mountainous terrain of eastern Cuba. The extent of the weakening that occurs, and whether Oscar remains a tropical cyclone (TC) once it emerges off the northern coast of Cuba, is still somewhat uncertain. The ECMWF has been the best-performing guidance for Oscar and shows it remaining a TC, while other models including the GFS suggest more significant weakening and possible degeneration to a surface trough. Even if Oscar survives, the environmental conditions over the southwestern Atlantic are expected to become more hostile, with stronger vertical wind shear and a drier surrounding airmass likely to inhibit much redevelopment. The NHC intensity forecast is similar to the previous one, but shows post-tropical status at 72 h given the shear. If Oscar survives that long, it should become absorbed by a larger, non-tropical low pressure system over the western Atlantic by 96 h. Key Messages: 1. 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. 2. Tropical storm conditions are expected to continue overnight across portions of eastern Cuba, where a Tropical Storm Warning is in effect. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 20.3N 74.6W 60 KT 70 MPH 12H 21/1200Z 20.4N 75.0W 50 KT 60 MPH...INLAND 24H 22/0000Z 20.9N 75.3W 40 KT 45 MPH...OVER WATER 36H 22/1200Z 21.9N 74.9W 40 KT 45 MPH 48H 23/0000Z 23.4N 73.7W 40 KT 45 MPH 60H 23/1200Z 25.1N 72.1W 40 KT 45 MPH 72H 24/0000Z 27.3N 70.2W 35 KT 40 MPH...POST-TROPICAL 96H 25/0000Z...DISSIPATED $$ Forecaster Reinhart