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| #1022940 (Received by flhurricane at: 5:26 AM 28.Oct.2020) TCDAT3 Hurricane Zeta Discussion Number 15 NWS National Hurricane Center Miami FL AL282020 400 AM CDT Wed Oct 28 2020 The satellite presentation of Zeta has improved significantly overnight with deep convection wrapping around an eye that at times as been fairly well defined. An Air Force Reserve Hurricane Hunter aircraft that has just began its reconnaissance mission into Zeta has reported a pressure that has fallen to 982 mb and a 25-30 n-mi-wide eye during it first pass through the center. It is somewhat surprising that the plane did not report stronger winds during its northeast eyewall pass given the improved satellite presentation, and using a blend of the aircraft data and recent objective and subjective satellite estimates yields and initial intensity of 75 kt. It is possible the winds have yet to catch up to the improved satellite appearance, but since Zeta will moving over warm waters and in a light wind shear environment this morning some additional strengthening is likely. Although cooler waters and increasing southwesterly upper-level winds over the northern Gulf of Mexico are likely to cause the cyclone`s intensity to level-off or even come down slightly, Zeta is expected to reach the northern Gulf coast as significant hurricane by late this afternoon. The NHC intensity forecast is at the upper-end of the guidance, a little above the latest HWRF prediction. After landfall, Zeta will weaken while it moves over the southeastern United States, but the cyclone is forecast to become an extratropical gale-force low pressure area off the Mid-Atlantic coast Thursday night. The post-tropical cyclone should be absorbed by frontal boundary over the western Atlantic on Friday. Zeta has turned north-northwestward and has begun to accelerate as anticipated. A vigorous upper-level low moving into west Texas will cause Zeta to accelerate north-northeastward today, which will bring the center of the hurricane over southeastern Louisiana by late this afternoon. The cyclone is expected to continue to accelerate ahead of the trough over the southeastern United States tonight and Thursday. The dynamical model are in very good agreement and the latest NHC track is a blend of the various global models. The new track forecast is very close the previous official forecast. Given Zeta`s acceleration near landfall, strong winds are likely to spread well inland along the northern Gulf coast this evening and tonight. KEY MESSAGES: 1. A life-threatening storm surge is expected along portions of the northern Gulf Coast by late today, 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 this afternoon 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 and central Alabama tonight due to Zeta`s fast forward speed. 3. Through Thursday, heavy rainfall is expected from portions of the central U.S. Gulf Coast into the Tennessee Valley, Ohio Valley, Southern to Central Appalachians, and Mid-Atlantic States near and in advance of Zeta. This rainfall will lead to flash, urban, small stream, and minor river flooding. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 25.1N 91.8W 75 KT 85 MPH 12H 28/1800Z 27.9N 91.1W 85 KT 100 MPH 24H 29/0600Z 32.8N 87.5W 50 KT 60 MPH...INLAND 36H 29/1800Z 37.5N 79.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 48H 30/0600Z 40.5N 67.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 30/1800Z...DISSIPATED $$ Forecaster Brown |