Critical Alert

Weather: TS Laura weakening as it tracks northeast in south-central US, Aug. 27. Landfall as post-tropical cyclone in Newfoundland, Canada, Aug. 31. view alert 

  • Alert Begins: 27 Aug 2020 11:58 PM UTC
  • Alert Expires: 01 Sep 2020 11:59 PM UTC
  • Categories: Cyclone
  • Incident: TS Laura
  • Affected Area(s): South-Central, Tennessee Valley, Ohio Valley, Mid-Atlantic, and Northeast regions, US; far eastern Canada (map)
  • Projected Landfall (Date): Southeastern Newfoundland, Canada (Aug. 30-31)
  • Center of Circulation: Approximately 130 km (81 miles) northeast of Shreveport, Louisiana
  • Maximum Sustained Winds: 45 knots (83 kph, 52 mph)

 

Summary

 

Hurricane Laura has weakened significantly, degrading to a tropical storm as it continues moving northward across the south-central US, Aug. 27. As of 1600 CDT, the storm's center of circulation was approximately 130 km (81 miles) northeast of Shreveport, Louisiana. Forecast models indicate Laura will weaken further into a tropical depression by early Aug. 28 as it tracks across Arkansas. The system will then veer eastward, remaining a tropical depression as it transits the Tennessee Valley, Ohio Valley, and Mid-Atlantic regions through Aug. 29. Laura will 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 toward the Canadian Maritimes through Aug. 31. Laura will make a close approach to Nova Scotia's east coast before making an additional landfall in eastern Newfoundland 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 Laura's forecast track and intensity, and changes in projection could occur over the coming days.

Government Advisories
As of 1600 CDT Aug. 27, all coastal watches and warnings have been canceled. Inland tropical storm warnings remain in effect for parts of northern Louisiana, southern Arkansas, and far-western Mississippi. 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. 

Hazardous Conditions
Laura will likely bring heavy rainfall and strong winds areas across the South-Central, Ohio Valley, Tennessee Valley, Mid-Atlantic, and Northeast regions of the US through Aug. 30, and the Canadian Maritimes and Newfoundland Aug. 30-31. 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. 

In addition to the heavy rain and flooding, gusts in excess of 55 knots (102 kph, 63 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. Isolated tornadoes in parts of the affected region over the coming days.

Transport
Inclement weather associated with the storm is likely to trigger ground, air, and maritime transport disruptions in areas along the system's track through Aug. 31. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and 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 including those serving Little Rock (LIT), Nashville (BNA), Lexington (LEX), Washington, DC (DCA, IAD), Baltimore (BWI), Halifax (YHZ), and St. John's (YYT). 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 tropical storm or other severe weather conditions. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the potential for flooding or 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.

Plan accordingly for 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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