- Incident: Major Hurricane Delta
- Location(s): Southern US (map)
- Projected Landfall (Date): Southwestern Louisiana, US (late Oct. 9)
- Center of Circulation: Approximately 55 km (35 miles) south of Cameron, Louisiana, US
- Maximum Sustained Winds: 90 knots (105 kph, 165 mph)
As of late Oct. 9, Hurricane Delta has weakened slightly as it continues to track northward in the Gulf of Mexico, as a Category-2 hurricane. As of 1600 CDT, the system's center of circulation was approximately 55 km (35 miles) south of Cameron, Louisiana, US. Forecast models indicate Delta will make landfall in southwestern Louisiana Oct. 9 before moving across central and northeastern Louisiana late Oct. 9 and early Oct. 10. Delta's remnants will likely bring heavy rainfall to portions of the southern US, including Arkansas, Mississippi, Tennessee, and Kentucky, through at least Oct. 11. Some uncertainty remains in the track and intensity forecast, and changes could occur over the coming days.
As of 1600 CDT Oct. 9, the following warnings are in effect:
- Hurricane Warning: High Island, Texas, to Morgan City, Louisiana
- Tropical Storm Warning: 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
- Storm Surge Warning: High Island, Texas, to the mouth of the Pearl River, including Calcasieu Lake, Vermilion Bay, and Lake Borgne
Authorities could issue new warnings or update/rescind existing advisories throughout the system's progression in the coming days. Weather warnings could remain active even after the system's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards. The possibility of localized evacuations cannot be discounted if weather conditions prove particularly hazardous. The proximity of the system's center of circulation to land will ultimately determine how significant the weather-related impacts will be; the greatest impacts will likely be felt just northeast of where the center passes.
In advance of Delta, a state of emergency is in effect for both Alabama and Louisiana. The following mandatory and voluntary evacuation orders have been issued:
- Mandatory Evacuations (Louisiana): Allen Parish; Beauregard Parish; Calcasieu Parish; Cameron Parish (except residents north of the Kelso Bayou in Hackberry); residents who live west of US Highway 90 and south of State Highway 14 in Iberia Parish; Jefferson Davis Parish; Grand Isle in Jefferson Parish; residents south of the Leon Theriot Floodgate in Golden Meadow and low-lying areas of Lafourche Parish; Abbeville and low-lying areas of Vermilion Parish; all areas south of Pointe-aux-Chenes Floodgate, south of the Bayou Terrebonne Floodgate, Isle de Jean Charles, south of the Bayou Petit Caillou Floodgate, south of the Morganza to the Gulf of Mexico levee road ramp in lower Dulac, and south of the Lower Dularge Floodgate in Terrebonne Parish; and south of the Intracoastal Waterway and west of the Wax Lake outlet in Saint Mary Parish
- Voluntary Evacuations (Louisiana): Acadia Parish; all portions of Iberia Parish not under mandatory evacuation orders; portions of Jefferson Parish, including Jean Lafitte, Lower Lafitte, Crown Point, and Barataria; Lafayette Parish; Port Fourchon in Lafourche Parish; City of New Orleans, including Venetian Isles, Lake Catherine, and Irish Bayou; Plaquemines Parish from White Ditch to Pointe a la Hache and from Phillips 66 Alliance Refinery to Venice; Port Fourchon in Lafourche Parish; Saint Landry Parish; Saint Martin Parish near Stephensville and Belle River; residents south of the Intercoastal Waterway and west of the Wax Lake outlet in Saint Mary Parish; and portions of Vermilion Parish south of State Highway 14
- Mandatory Evacuations (Alabama): Orange Beach, Gulf Shores, Dauphin Island, Ono Island, and Fort Morgan
Hurricane Delta will likely bring heavy rainfall, gusty winds, and high waves to portions of the Gulf Coast beginning Oct. 9. Widespread rain accumulations around 13-25 cm (5-10 inches) are forecast across the southwestern and into central Louisiana. Locally higher rainfall totals up to 38 cm (15 inches) are possible in areas affected by persistent bands of thunderstorms. Rainfall totals of 8-15 cm (3-6 inches) are expected in far eastern Texas into northern Louisiana, southern Arkansas, and western Mississippi, with higher totals of up to 25 cm (10 inches) possible where the most persistent heavy rain bands occur. Additionally, rainfall accumulations of 2.5-7.5 cm (1-3 inches) are possible across the Tennessee Valley and Mid-Atlantic over the coming days. The Southern Appalachians could experience between 8-15 cm (3-6 inches) of rainfall over the coming days.
Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding as the system approaches the islands. A persistent onshore flow could make it difficult for the surge to recede, and water levels decrease in coastal river catchments.
The greatest impacts in terms of strong winds and storm surge will be felt just to the east of the center of circulation relative to the storm's track. This is partly due to the counterclockwise circulation of a hurricane in the northern hemisphere, which allows for a higher storm surge because the winds help bring additional water on to the shore. Forecast models indicate life-threatening storm surge totals of 2.1-3.4 meters (7-11 feet) are expected from Rockefeller Wildlife Refuge to Morgan City, Louisiana, including Vermilion Bay; surge of 1.5-2.4 meters (5-8 feet) is expected from Holly Beach to Rockefeller Wildlife Refuge, Louisiana. Sabine Pass to Holly Beach, Louisiana are expected to experience 0.9-1.5 meters (3-5 feet) of surge. Calcasieu Lake; High Island, Texas to Sabine Pass; Port Fourchon, Louisiana to the Mouth of the Pearl River, and Lake Borgne are forecast to experience 0.6-1.2 meters (2-4 feet) of surge. Lake Pontchartrain and Lake Maurepas; the mouth of the Pearl River to the Alabama-Florida Border, including MobileBay; Sabine Lake; and Port O'Connor, Texas, to High Island, Texas, including Galveston Bay, may experience surge levels of 0.3-0.9 meters (1-3 feet).
In addition to the heavy rain, flooding, and storm surge, the system is likely to produce damaging wind gusts as its center approaches the Gulf Coast. Hurricane-force gusts over 90 knots (165 kph, 100 mph) are possible along the Gulf Coast of the US near where the center of Delta makes landfall, including south-central and southwestern Louisiana; tropical-storm-force gusts in excess of 45 knots (85 kph, 50 mph) cannot be ruled out farther inland, as well as in far southeastern Texas and southeastern Louisiana. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are possible. Rain-induced landslides are also possible in hilly areas where the ground is loose and unstable, especially in areas where heavy rainfall occurred during previous tropical systems, including Hurricane Laura. Additionally, Hurricane Delta will likely produce tornadoes, especially in southern Louisiana and southern Mississippi, over the coming days.
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions over the coming days. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. Heavy rain and low visibility may trigger flight disruptions at regional airports.
Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.
Activate contingency plans in areas where officials forecast hurricane or tropical storm conditions. Heed all evacuation orders. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks. Keep any necessary medications in a waterproof container.
Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.