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| #1022866 (Received by flhurricane at: 4:45 PM 27.Oct.2020) TCDAT3 Tropical Storm Zeta Discussion Number 13 NWS National Hurricane Center Miami FL AL282020 400 PM CDT Tue Oct 27 2020 Visible satellite images show that the low-level center of the storm is slightly displaced to the north of the main area of deep convection. Since the organization of the tropical cyclone has not yet improved, the current intensity is held at 55 kt, which is a blend of subjective and objective Dvorak estimates. Zeta should move over warm waters and through a moist, low-shear environment through tomorrow morning, so strengthening is anticipated, and the cyclone is likely to regain hurricane intensity within the next 6-12 hours. The NHC intensity forecast is on the high side of the model guidance suite. Zeta is expected to interact with a frontal zone and become an extratropical cyclone as it approaches the eastern United States in a couple of days. After moving off the U.S. east coast, the system is forecast to become absorbed by the same frontal system. Zeta continues to move northwestward, or at about 310/12 kt. The expected large-scale steering flow evolution remains about the same as before. Zeta is expected to turn northward and move along the western side of a mid-level anticyclone centered east of Florida through Wednesday morning. Then, a vigorous 500-mb shortwave trough approaching from the west should cause Zeta to accelerate north- northeastward and move inland along the central Gulf Coast by late Wednesday. The cyclone should continue to accelerate ahead of the trough and move over the southeastern and eastern U.S. through Thursday. The official track forecast was nudged just slightly westward in 24 to 36 hours to be in better agreement with the latest GFS and ECMWF explicit model fields. Given Zeta`s acceleration near landfall, strong winds are likely to spread well inland along the northern Gulf coast Wednesday night. KEY MESSAGES: 1. A life-threatening storm surge is expected along portions of the northern Gulf Coast by late Wednesday, with the highest inundation occurring somewhere between the Mouth of the Pearl River and Dauphin Island, Alabama. Residents in the Storm Surge Warning area should follow any advice given by local officials. 2. Hurricane conditions are expected by late Wednesday within portions of the Hurricane Warning area between Morgan City, Louisiana, and the Mississippi/Alabama border. Damaging winds, especially in gusts, will spread well inland across portions of southeast Mississippi and southern Alabama Wednesday night due to Zeta`s fast forward speed. 3. Localized heavy rainfall from Zeta will continue tonight in portions of the Yucatan Peninsula of Mexico and western Cuba where additional flash flooding is possible in urban areas. Tonight through Thursday heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Ohio Valley and Mid-Atlantic States. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 22.7N 90.3W 55 KT 65 MPH 12H 28/0600Z 24.5N 91.3W 70 KT 80 MPH 24H 28/1800Z 27.9N 91.0W 70 KT 80 MPH 36H 29/0600Z 32.4N 87.8W 45 KT 50 MPH...INLAND 48H 29/1800Z 37.2N 81.3W 30 KT 35 MPH...POST-TROP/EXTRATROP 60H 30/0600Z 40.0N 70.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 30/1800Z...DISSIPATED $$ Forecaster Pasch |