Critical Alert

Weather: Hurricane Laura continues to track north in the Gulf Coast region, US, early Aug. 27 following landfall in Cameron, La., early Aug. 27. 
 

  • Alert Begins: 27 Aug 2020 11:16 AM UTC
  • Alert Expires: 01 Sep 2020 11:59 PM UTC
  • Incident: Hurricane Laura
  • Affected Area(s): Gulf Coast, Tennessee Valley, Ohio Valley, Mid-Atlantic, and Northeast regions, US; far eastern Canada (map)
  • Projected Landfall (Date): Eastern Nova Scotia, Canada (Aug. 30-31)
  • Center of Circulation: Approximately 50 km (30 miles) north-northwest of Lake Charles, Louisiana
  • Maximum Sustained Winds: 105 knots (195 kph, 120 mph)

 

Summary

 

Hurricane Laura has weakened slightly to a Category-3 Hurricane over southwestern Louisiana early Aug. 27 following landfall near Cameron, Louisiana, as a Category-4 system. As of 0400 CDT, the storm's center of circulation was approximately 50 km (30 miles) north-northwest of Lake Charles, Louisiana. Forecast models indicate Hurricane Laura will continue to weaken into a tropical storm as it tracks northward into northwestern Louisiana and Arkansas through Aug. 27. Hurricane Laura will continue to weaken into a depression and veer eastward toward the Tennessee Valley, Ohio Valley, and Mid-Atlantic regions through Aug. 29, and enter the Atlantic Ocean by late Aug. 29-early Aug. 30. The storm is then forecast to strengthen slightly into a post-tropical cyclone with tropical storm-force winds off the coast of the Mid-Atlantic region before tracking northeastward toward far eastern Canada through Sept. 1. An additional landfall is forecast in eastern Nova Scotia as a post-tropical cyclone Aug. 30-31; however, the guidance is highly varied, and there is low confidence in the forecast, especially about potential impacts in Canada. Some uncertainty remains in Hurricane Laura's forecast track and intensity, and changes in projection could occur over the coming days.

Government Advisories
As of 0400 CDT Aug. 27, the following advisories have been issued in response to the storm:

  • Hurricane Warning: High Island, Texas to Intracoastal City, Louisiana
  • Tropical Storm Warning: East of Intracoastal City, Louisiana to the Mouth of the Mississippi River
  • Storm Surge Warning: High Island, Texas to the Mouth of the Mississippi River


Authorities will likely issue new warnings or update 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. 

Evacuations
In response to Hurricane Laura, over 750,000 people across southern Louisiana and southeastern Texas have been urged to evacuate. Authorities in Louisiana have issued evacuation orders for portions of Calcasieu, Terrebone, Cameron, Jefferson, Lafourche, and Plaquemines parishes. Additionally, authorities have issued evacuation orders for portions of southeastern Texas, including Chambers, Galveston, Hardin, Jasper, Jefferson, Newton, and Orange counties. Further evacuations are likely along the Gulf Coast as Hurricane Laura impacts the region. The governors of both Louisiana and Texas have issued states of emergency in anticipation of the system. Additionally, both states have closed down schools and other government offices in anticipation of the storm.

Hazardous Conditions
Hurricane Laura will likely bring heavy rainfall and strong winds areas across the Gulf Coast, Ohio Valley, Tennessee Valley, Mid-Atlantic, and Northeast regions of the eastern US Aug. 26-30, and eastern Canada Aug. 30-Sept. 1. High seas will also occur in coastal areas. Forecast models indicate widespread rainfall totals of 15-30 cm (6-12 inches) are expected across portions of Louisiana, Mississippi, and Arkansas. Locally higher totals of up to 46 cm (18 inches) are possible in the hardest-hit areas. Totals of 2.5-8 cm (1-3 inches) are expected in the mid-Mississippi Valley, portions of the Tennessee and Lower Ohio Valley, central Appalachians, and the Mid-Atlantic region. Locally higher totals of 13 cm (5 inches) are possible in the hardest-hit areas of this region. 

Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, and rivers, as well as in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides cannot be discounted in steeply sloped terrains. 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 tracks close to land. Persistent onshore flow could make it difficult for surge to recede and for water levels to decrease in coastal river catchments. 

Life-threatening storm surge could raise water levels to 4.5-6 meters (15-20 feet) above sea level from Johnson Bayou to Rockefeller Wildlife Refuge including Calcasieu Lake. Forecast models indicate storm surge levels of 3-4.5 meters (10-15 feet) are possible from Rockefeller Wildlife Refuge to Intracoastal City. Intracoastal City to Morgan City including Vermilion Bay is forecast to receive between 2.4-3.7 meters (8-12 feet). Possible storm surge values of 1.2-2.4 meters (4-8 feet) are possible from Sea Rim State Park to Johnson Bayou including Sabine Lake. From Morgan City to the mouth of the Mississippi River storm surge totals of 1.2-2.1 meters (4-7 feet) are forecast. Storm surge levels of 0.6-1.2 meters (2-4 feet) are forecast from High Island to Sea Rim State Park. Additionally, storm surge totals of 0.3-0.9 meters (1-3 feet) are forecast from the mouth of the Mississippi River to Ocean Springs, Lake Borgne, Lake Pontchartrain, and Lake Maurepas. Storm surge could penetrate up to 64 km (40 miles) inland and may not recede for several days, especially from Sea Rim State Park, Texas, to Intracoastal City, Louisiana, including Calcasieu and Sabine Lakes, where the highest levels of storm surge are forecast to occur.

In addition to the heavy rain, flooding, rough surf, and storm surge, Hurricane Laura is also likely to produce hurricane-force wind gusts along the immediate Gulf Coast and tropical-storm-force winds farther inland. Gusts in excess of 130 knots (240 kph, 150 mph) cannot be ruled out, especially in areas near the center of circulation. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are likely. Report indicate over 300,00 customers are without power across Texas and Louisiana. Isolated tornadoes are possible across the Gulf Coast region including Louisiana, southeastern Texas, Arkansas, and western Mississippi over the coming days.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm is likely to trigger severe ground, air, and maritime transport disruptions are likely across the affected areas, Aug. 26-Sept. 1. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Reports indicate portions of Interstate 10 are closed from the Louisiana/Texas border to Atchafalaya Basin. 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 including those serving New Orleans (MSY), Houston (IAH), and Little Rock (LIT). 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.

 

Advice

 

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.
 


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