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| #1020273 (Received by flhurricane at: 11:12 AM 07.Oct.2020) TCDAT1 Hurricane Delta Discussion Number 12 NWS National Hurricane Center Miami FL AL262020 1000 AM CDT Wed Oct 07 2020 Satellite and surface observations show that Delta made landfall along the northeastern coast of the Yucatan peninsula around 1030 UTC near Puerto Morelos. A WeatherFlow observing site at Puerto Morelos reported near calm winds and a minimum pressure of around 972 mb when the center passed that location. Another WeatherFlow site near Cancun reported peak sustained winds of 73 kt with a gust to 92 kt. Hurricane-force winds gusts were also reported at an observing site on Cozumel. Since landfall, Delta has moved across the northeastern portion of the Yucatan peninsula and is now about the emerge off the northern coast of the peninsula into the southern Gulf of Mexico. Assuming some weakening has occurred, the initial intensity has been set at 90 kt, but this could be a little generous. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Delta early this afternoon. A NOAA P-3 aircraft has been preforming a Tail Doppler Radar mission this morning. Once Delta moves over the southern Gulf of Mexico, warm waters and expected low vertical wind shear conditions are expected to allow for re-strengthening during the next 24 to 36 hours. After 48 hours, increasing southwesterly shear and cooler waters over the northern Gulf are likely to induce some weakening. The intensity guidance has trended downward this cycle, and the NHC forecast has been adjusted accordingly. Delta, however is still expected to regain major hurricane status and the wind field is likely to grow in size during its approach to the northern Gulf coast, which will increase the storm surge and wind threats. Regardless of Delta`s landfall intensity, life-threatening storm surge and strong winds are likely over a large portion of the northwestern and northern Gulf coast, which has necessitated the issuance of Storm Surge, Hurricane, and Tropical Storm watches for portions of that area. Delta is moving northwestward or 305/15 kt. The hurricane should continue moving northwestward around the southwestern portion of a subtropical ridge that extends over Florida and the northeastern Gulf of Mexico through early Thursday. After that time, a developing mid-level trough over the south-central United States should cause Delta to slow down and turn north-northwestward on Thursday. Delta is forecast to begin accelerating northward or north-northeastward toward the northern Gulf coast ahead of the trough Thursday night and Friday. There has been little change to the early portion of the track forecast, but there has been a little westward shift in the guidance envelope after 24 hours, and the NHC forecast has been moved in that direction. The new forecast track lies near or just left of the TVCA multi-model consensus and a little right of the HFIP corrected consensus aid, again close to the GFS, GFS ensemble mean, and UKMet models. Key Messages: 1. Life-threatening storm surge and dangerous winds will continue within portions of the northern Yucatan Peninsula of Mexico into early afternoon. Heavy rainfall, which could lead to significant flash flooding, will affect the northern Yucatan Peninsula through early Thursday. 2. Delta is expected to grow in size as it approaches the northern Gulf Coast, where there is an increasing likelihood of life- threatening storm surge and dangerous hurricane-force winds beginning Friday, particularly for portions of the Louisiana coast. Storm Surge and Hurricane Watches are in effect, and residents in these areas should follow advice given by local officials. 3. Flash, urban, small stream, and minor river flooding is likely Friday through Saturday from portions of the central Gulf Coast northward into portions of the Lower to Middle Mississippi Valley. As Delta moves farther inland, additional heavy rainfall is expected in the Ohio Valley and Mid Atlantic this weekend. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 21.4N 88.0W 90 KT 105 MPH...INLAND 12H 08/0000Z 22.8N 90.2W 95 KT 110 MPH...OVER WATER 24H 08/1200Z 24.3N 92.4W 100 KT 115 MPH 36H 09/0000Z 26.0N 93.3W 105 KT 120 MPH 48H 09/1200Z 28.1N 93.3W 105 KT 120 MPH 60H 10/0000Z 30.8N 92.4W 70 KT 80 MPH...INLAND 72H 10/1200Z 33.2N 90.9W 40 KT 45 MPH...INLAND 96H 11/1200Z 36.5N 86.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 12/1200Z 39.5N 81.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown |