| Track: https://www.nhc.noaa.gov/refresh/graphics_at1+shtml/?cone#contents Satellite: https://rammb-data.cira.colostate.edu/tc_realtime/storm.asp?storm_identifier=al262020 https://www.star.nesdis.noaa.gov/GOES/floater.php?stormid=AL262020 Hurricane Delta Discussion Number 18 NWS National Hurricane Center Miami FL AL262020 1000 PM CDT Thu Oct 08 2020 Reports from Air Force and NOAA Hurricane Hunter aircraft investigating Delta indicate that the hurricane strengthened a little more this evening. Peak flight-level winds were 120 kt, and the highest SFMR-observed surface winds were 98 kt. Using a blend of adjusted flight-level and surface wind observations, the current intensity estimate is set at 105 kt. The eye became obscured on satellite images a couple of hours ago, but recently it has become apparent again. Delta could intensify a little more within the next 6 hours or so. Thereafter, sharply decreasing oceanic heat content, significantly increasing west-southwesterly shear, and drier mid-level air should cause weakening. The official intensity forecast through landfall is above most of the model guidance. However, even 24-hour tropical cyclone intensity forecasts are still subject to an uncertainty of 1 Saffir-Simpson category, so one should not focus on the exact official landfall intensity forecast. Moreover, even if Delta weakens some, it will still have serious storm surge impacts due to its large size. Aircraft and satellite center fixes show that the hurricane is gradually turning toward the right. The motion is now north-northwestward, or 340/10 kt. Delta should turn northward on Friday as it moves on the western side of a mid-tropospheric high pressure area. Later on Friday, a 500-mb shortwave trough over the southern United States is likely to cause the tropical cyclone to turn north-northeastward and cross the northern Gulf of Mexico coast. Delta should then move northeastward on the eastern side of the trough over the southeastern United States for the next day or two before dissipating near Kentucky. The official track forecast is very close to the previous NHC track, and in very good agreement with the various consensus track predictions. Key Messages: 1. Life-threatening storm surge is expected near and east of where Delta makes landfall 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 Morgan City, 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 a relatively large hurricane. 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. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana Friday and Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 25.7N 93.6W 105 KT 120 MPH 12H 09/1200Z 27.4N 93.7W 105 KT 120 MPH 24H 10/0000Z 29.8N 93.0W 85 KT 100 MPH...INLAND 36H 10/1200Z 32.0N 91.9W 45 KT 50 MPH...INLAND 48H 11/0000Z 33.5N 90.2W 25 KT 30 MPH...INLAND 60H 11/1200Z 34.9N 88.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 12/0000Z 36.5N 87.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 13/0000Z...DISSIPATED $$ Forecaster Pasch/Berg Hurricane Delta Advisory Number 18 NWS National Hurricane Center Miami FL AL262020 1000 PM CDT Thu Oct 08 2020 ...DELTA STRENGTHENS A LITTLE MORE... ...EXPECTED TO BRING HURRICANE CONDITIONS AND A LIFE-THREATENING STORM SURGE TO PORTIONS OF THE NORTHERN GULF COAST ON FRIDAY... SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...25.7N 93.6W ABOUT 285 MI...455 KM S OF CAMERON LOUISIANA MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H PRESENT MOVEMENT...NNW OR 340 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...955 MB...28.20 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * High Island Texas to Ocean Springs Mississippi including Calcasieu Lake, Vermilion Bay, Lake Pontchartrain, Lake Maurepas, and Lake Borgne A Hurricane Warning is in effect for... * High Island Texas to Morgan City Louisiana A Tropical Storm Warning is in effect for... * West of High Island to Sargent Texas * East of Morgan City Louisiana to the mouth of the Pearl River, including New Orleans * Lake Pontchartrain and Lake Maurepas A Tropical Storm Watch is in effect for... * East of the mouth of the Pearl River to Bay St. Louis Mississippi A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm- force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area. For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 1000 PM CDT (0300 UTC), the center of Hurricane Delta was located near latitude 25.7 North, longitude 93.6 West. Delta is moving toward the north-northwest near 12 mph (19 km/h). A turn toward the north is forecast overnight, followed by a north-northeastward motion Friday and Friday night. On the forecast track, the center of Delta will move over the northwestern Gulf of Mexico on Friday, and then move inland within the hurricane warning area Friday afternoon or Friday night. Maximum sustained winds have increased to near 120 mph (195 km/h) with higher gusts. Delta is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some slight additional strengthening is possible overnight. Weakening is expected to begin as Delta approaches the northern Gulf coast on Friday, with rapid weakening expected after the center moves inland. Hurricane-force winds extend outward up to 40 miles (65 km) from the center and tropical-storm-force winds extend outward up to 160 miles (260 km). NOAA buoy 42002 near Delta's northwestern eyewall recently reported a sustained wind of 63 mph (101 km/h) and a wind gust to 76 mph (122 km/h). The buoy also reported a significant wave height just over 29 feet (almost 9 meters). The minimum central pressure reported by an Air Force Hurricane Hunter Aircraft is 955 mb (28.20 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Delta can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT1, WMO header WTNT41 KNHC, and on the web at www.hurricanes.gov/text/MIATCDAT1.shtml. STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Rockefeller Wildlife Refuge, LA to Morgan City, LA including Vermilion Bay...7-11 ft Holly Beach, LA to Rockefeller Wildlife Refuge, LA...5-8 ft Sabine Pass to Holly Beach, LA...4-7 ft Morgan City, LA to Port Fourchon, LA...4-7 ft Port Fourchon, LA to the Mouth of the Mississippi River...3-5 ft Calcasieu Lake...3-5 ft High Island, TX to Sabine Pass...2-4 ft Mouth of the Mississippi River to Ocean Springs, MS...2-4 ft Lake Borgne, Lake Pontchartrain, and Lake Maurepas...2-4 ft Ocean Springs, MS to the AL/FL border including Mobile Bay...1-3 ft Sabine Lake...1-3 ft Port O'Connor, TX to High Island, TX including Galveston Bay... 1-3 ft It is important to note that small changes in the track, structure, or intensity of Delta could have large impacts on where the highest storm surge occurs. Users are urged to stay tuned for possible changes and updates. The deepest water will occur along the immediate coast near and to the east of the landfall location, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. WIND: Hurricane conditions are expected within the hurricane warning area by Friday afternoon or evening, with tropical storm conditions expected within this area by early Friday. Tropical storm conditions are expected within the tropical storm warning areas on Friday, and are possible within the tropical storm watch area Friday night. RAINFALL: Friday through Saturday, Delta is expected to produce 5 to 10 inches of rain, with isolated maximum totals of 15 inches, from southwest into south-central Louisiana. These rainfall amounts will lead to significant flash, urban, small stream flooding, along with minor to major river flooding. For extreme east Texas into northern Louisiana, southern Arkansas and western Mississippi, Delta is expected to produce 3 to 6 inches of rain, with isolated maximum totals of 10 inches. These rainfall amounts will lead to flash, urban, small stream and isolated minor river flooding. As Delta moves farther inland, 1 to 3 inches of rain, with locally higher amounts, are expected in the Tennessee Valley and Mid- Atlantic this weekend. TORNADOES: There is a risk of a few tornadoes beginning late tonight and continuing through Friday over southern portions of Louisiana and Mississippi. SURF: Swells from Delta are affecting portions of the northern and western Gulf coast. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 100 AM CDT. Next complete advisory at 400 AM CDT. $$ Forecaster Pasch |