Major Hurricane Delta Heading To Southeastern Louisiana

Hurricane Delta continues to strengthen in the Gulf of Mexico, now a Category 3 Hurricane on the Saffir-Simpson Hurricane Wind Scale. This powerful hurricane is forecast to make landfall across Southeastern Louisiana on Friday evening.

Delta is the 9th hurricane of the 2020 Atlantic Hurricane Season and the 3rd major hurricane. It is also the 26th tropical cyclone of the 2020 Atlantic Hurricane Season and the earliest 25th named storm in Atlantic history. The previous record for the 25th named storm was Gamma, on November 15th, 2005. The last (and only) time Delta was used in the Atlantic was on November 22nd, 2005.

This tropical cyclone is not forecast to impact Trinidad, Tobago, or the Lesser Antilles.

List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Epsilon.

At 11:00 PM AST, 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 millibars.

Hurricane Delta Forecast Track as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)
Hurricane Delta Forecast Track as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)

Watches & Warnings

Hurricane Delta Watches and Warnings as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)
Hurricane Delta Watches and Warnings as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)

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.

Hazards Affecting Land

Hurricane Delta Storm Surge forecast as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)
Hurricane Delta Storm Surge forecast as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)

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 large and dangerous waves will accompany the surge. Surge-related flooding depends on the relative timing of the surge and the tidal cycle and can vary greatly over short distances. Please see products issued by your local National Weather Service forecast office for information specific to your area.

Hurricane Delta robabilities for tropical-storm-force winds as of 11:00 PM AST Thursday 8th October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Hurricane Delta robabilities for tropical-storm-force winds as of 11:00 PM AST Thursday 8th October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

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.

Hurricane Delta rainfall forecast as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)
Hurricane Delta rainfall forecast as of 11:00 PM AST Thursday 8th October 2020. (National Hurricane Center)

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.

This system is of no direct threat to the Windward Islands, including Trinidad and Tobago.

Hurricane Delta Forecast Discussion

Hurricane Delta (Weathernerds.org)
Hurricane Delta (Weathernerds.org)

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 agrees with the various consensus track predictions.

Key Messages for Hurricane Delta (National Hurricane Center)
Key Messages for Hurricane Delta (National Hurricane Center)

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 the 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 discussion by NHC Forecaster Pasch/Berg.

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