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| #1022690 (Received by flhurricane at: 11:06 AM 26.Oct.2020) TCDAT3 Tropical Storm Zeta Discussion Number 8 NWS National Hurricane Center Miami FL AL282020 1000 AM CDT Mon Oct 26 2020 After a significant strengthening episode early this morning, Zeta appears to have changed little in intensity recently. High spatial and temporal resolution GOES-16 visible satellite images indicate that the low-level center of the storm is located near the northwestern edge of the main area of vigorous deep convection. The current intensity estimate is held at 60 kt which is the average of recent Dvorak estimates from TAFB and SAB. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Zeta in a few hours, and should provide a better estimate of the strength of the storm. Zeta is moving northwestward, or about 305/9 kt. A mid-level high pressure area centered just east of Florida should steer the tropical cyclone on a continued northwestward heading for the next day or so, taking center over the northern part of the Yucatan Peninsula. By around 48 hours, Zeta is expected to turn northward over the Gulf along the western side of the high. Afterward, a shortwave trough moving into the southern Plains should induce a turn toward the north-northeast and take the center inland over the southern United States. The system should then move fairly quickly northeastward across the eastern U.S. and emerge into the Atlantic by day 4. The official track forecast has been adjusted a bit to the west of the previous one but not quite as far west as the corrected model consensus. Zeta is apparently experiencing some north-northwesterly shear given the displacement of the low-level center from the convection. However, this shear is expected to abate very soon, and the cyclone is likely to strengthen into a hurricane before reaching the northeastern Yucatan Peninsula. Some weakening should occur while Zeta interacts with land during the next 12 to 24 hours. The atmospheric and oceanic environment should be somewhat conducive while the system moves over the southern Gulf of Mexico in a day or two, and the official forecast shows some re-strengthening in 24-36 hours. Later in the forecast period, when Zeta approaches the northern Gulf Coast, cooler shelf waters and some increase in southwesterly shear could cause some weakening. The official intensity forecast is similar to the previous ones and shows Zeta still near hurricane strength at landfall along the northern Gulf of Mexico coast, which is near or above most of the model guidance. Zeta is likely to become an extratropical cyclone when it emerges into the Atlantic, and be absorbed by a frontal system around the end of the forecast period. Given the timing of the track and the forecast wind radii, watches will likely be required for a portion of the northern Gulf Coast later today. KEY MESSAGES: 1. Hurricane conditions and dangerous storm surge are expected in portions of the northern Yucatan Peninsula of Mexico tonight and early Tuesday. Tropical storm conditions could occur over extreme western Cuba beginning later today. 2. Through Tuesday, heavy rainfall is expected from Zeta across the Yucatan Peninsula of Mexico, the Cayman Islands, and central to western Cuba. This rainfall may lead to flash flooding in urban areas. Between Tuesday night and Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the southern Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. 3. Zeta is forecast to be at or near hurricane strength when it approaches the northern Gulf Coast on Wednesday, and there is an increasing risk of dangerous storm surge, wind, and rainfall impacts from Louisiana to the Florida Panhandle. Residents in these areas should monitor the progress of Zeta, as Hurricane and Storm Surge watches will likely be issued later today. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 19.1N 85.3W 60 KT 70 MPH 12H 27/0000Z 20.1N 86.7W 75 KT 85 MPH 24H 27/1200Z 21.5N 88.8W 65 KT 75 MPH 36H 28/0000Z 23.3N 90.8W 70 KT 80 MPH 48H 28/1200Z 25.7N 91.8W 70 KT 80 MPH 60H 29/0000Z 28.9N 90.7W 65 KT 75 MPH 72H 29/1200Z 33.0N 87.0W 35 KT 40 MPH...INLAND 96H 30/1200Z 40.0N 73.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 31/1200Z...DISSIPATED $$ Forecaster Pasch |