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| #1020427 (Received by flhurricane at: 10:57 AM 08.Oct.2020) TCDAT1 Hurricane Delta Discussion Number 16 NWS National Hurricane Center Miami FL AL262020 1000 AM CDT Thu Oct 08 2020 Satellite imagery shows that Delta is better organized this morning, with the center well embedded in a cold central dense overcast and a hint of a eye developing in the overcast. Reports from Air Force Reserve and NOAA Hurricane hunter aircraft indicate that the central pressure has fallen to 968 mb inside a 35 n mi wide eye, along with flight-level and SFMR winds that support an initial intensity of 90 kt. The initial motion remains northwestward or 305/12 kt. The track forecast is reasonably straightforward. During the next 12-24 h, Delta should turn to the north between a mid- to upper-level ridge over the Florida Peninsula and eastern Gulf of Mexico and a mid- to upper-level level trough over the U.S. Southern Plains. This should be followed by a north-northeastward motion that is expected to bring the center near or over the northern Gulf coast, most likely in southwestern Louisiana, in about 36 h. After landfall, the cyclone should move northeastward through the Lower Mississippi and Tennessee Valleys along the southern edge of the mid-latitude westerlies until it dissipates. The track guidance is very tightly clustered in terms of direction, and the new forecast track has only minor tweaks from the previous one. Shear, sea surface temperature, and moisture conditions appear favorable for strengthening during the next 12-24 h or so, and based on this Delta is expected to regain major hurricane strength. Rapid intensification cannot be ruled out, although the various rapid intensification indices do not suggest a high chance, and the first 24 h of the forecast is already above the intensity guidance. The global models forecast strong southwesterly shear developing over the hurricane during the last 12 h before landfall, and based on this some weakening is forecast. Rapid weakening is expected after landfall, with Delta forecast to degenerate to a remnant low by 72 h and dissipate shortly after that. It should be noted that the NHC 1-2 day intensity forecasts are subject to errors of around 1 Saffir-Simpson category. Delta is expected to grow in size as it approaches the Louisiana coast. The NHC wind radii forecast again follows a consensus of the global and hurricane regional models. Key Messages: 1. Life-threatening storm surge is expected near and east of where Delta makes landfall on Friday, and a Storm Surge Warning is in effect from High Island, Texas, to Ocean Springs, Mississippi. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Port Fourchon, Louisiana. Residents in the warning area should promptly follow advice given by local officials. The storm surge risk remains high despite the forecast decrease in intensity before landfall since Delta is expected to grow in size. 2. Hurricane-force winds are expected Friday afternoon and evening somewhere within the Hurricane Warning area between High Island, Texas, and Morgan City, Louisiana. Hurricane-force winds will also spread inland across portions of southern Louisiana near the path of Deltas center Friday evening and Friday night. 3. Significant flash flooding and minor to moderate river flooding are likely in parts of Louisiana Friday and Saturday, with additional flooding in portions of the central Gulf Coast into the Lower Mississippi Valley. FORECAST POSITIONS AND MAX WINDS INIT 08/1500Z 24.0N 92.7W 90 KT 105 MPH 12H 09/0000Z 25.4N 93.6W 95 KT 110 MPH 24H 09/1200Z 27.5N 93.8W 100 KT 115 MPH 36H 10/0000Z 29.8N 93.1W 90 KT 105 MPH...ON THE COAST 48H 10/1200Z 32.4N 91.7W 45 KT 50 MPH...INLAND 60H 11/0000Z 34.0N 90.0W 30 KT 35 MPH...INLAND 72H 11/1200Z 35.6N 87.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 12/1200Z...DISSIPATED $$ Forecaster Beven |