Issued at 500 AM EDT Mon Oct 21 2024
000 WTNT41 KNHC 210837 TCDAT1 Tropical Storm Oscar Discussion Number 9 NWS National Hurricane Center Miami FL AL162024 500 AM EDT Mon Oct 21 2024 The center of Oscar has continued to move over eastern Cuba overnight. Although radar imagery from Guantanamo Bay has shown a continued degradation of Oscar's inner core, bands of deep convection with heavy rainfall remain over portions of the island. A couple of ASCAT passes from earlier in the night showed that tropical-storm-force winds were occurring along both the southern and northern coasts of eastern Cuba. Given the decrease in inner core organization over the past several hours, the initial wind speed has been lowered perhaps conservatively to 45 kt for this advisory. Radar and surface observations from Guantanamo Bay indicate that the center is located just north of that location. The initial motion estimate is a somewhat uncertain 270/2 kt. The storm should begin to turn northwestward and northward later today ahead of a shortwave trough moving over the northwestern Bahamas. Some of the dynamical model guidance suggests that the center may re-form near the northern coast of Cuba later today, rather than the low-level center continuously tracking across the mountainous terrain of the island. Regardless of the details of the track over eastern Cuba, Oscar is expected to emerge off the northern coast of Cuba later today or tonight. Thereafter, the cyclone should accelerate northeastward over portions of the southeastern Bahamas and western Atlantic ahead of the aforementioned trough. In 60-72 hours, global model guidance indicates that the circulation will become elongated and that it will be absorbed by a larger developing non-tropical area of low pressure between Bermuda and the southeastern U.S. coast by day 3. The track guidance is again faster this cycle, and the NHC forecast has been adjusted accordingly. Additional weakening is expected while Oscar moves over eastern Cuba today. Most of the guidance now keeps Oscar a tropical cyclone after it emerges off the northern coast of Cuba, but increasing westerly vertical wind shear and dry mid-level air should prevent significant restrengthening before it is absorbed by a non-tropical area of low pressure. The primary hazard associated with Oscar will be heavy rainfall and life-threatening flash flooding, particularly over the mountainous terrain of eastern Cuba. Key Messages: 1. Through midweek, heavy rainfall from Oscar will lead to areas of significant, 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 today across portions of eastern Cuba. Tropical storm conditions are also expected in portions of the southeastern Bahamas tonight and Tuesday. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 20.2N 75.1W 45 KT 50 MPH...INLAND 12H 21/1800Z 20.6N 75.3W 40 KT 45 MPH...INLAND 24H 22/0600Z 21.5N 75.0W 40 KT 45 MPH...OVER WATER 36H 22/1800Z 22.9N 74.0W 40 KT 45 MPH 48H 23/0600Z 24.5N 72.4W 40 KT 45 MPH 60H 23/1800Z 26.7N 70.2W 40 KT 45 MPH 72H 24/0600Z...ABSORBED BY NON-TROPICAL LOW PRESSURE AREA $$ Forecaster Brown
