Critical Alert

Weather: TD 13 strengthens into Tropical Storm Laura, Aug. 21. Landfall to occur in the northern Leeward Islands and Puerto Rico, Aug. 22.

  • Alert Begins: 21 Aug 2020 10:31 PM UTC
  • Alert Expires: 26 Aug 2020 11:59 PM UTC
  • Incident: Tropical Storm Laura
  • Affected Area(s): Caribbean and southeastern US (map)
  • Projected Landfall (Date): Leeward Islands and Puerto Rico (Aug. 22), Dominican Republic (Aug. 23), possibly Cuba (Aug. 24)
  • Center of Circulation: Approximately 70 km (43 miles) east of St. John's, Antigua and Barbuda
  • Maximum Sustained Winds: 40 knots (75 kph, 55 mph)

 

Summary

Tropical Depression 13 has strengthened into Tropical Storm Laura, Aug. 21, as it tracks toward the northern Leeward Islands. As of 1700 AST, the storm's center of circulation was approximately 70 km (43 miles) east of St. John's, Antigua and Barbuda. Forecast models indicate the storm may gradually strengthen a bit as it makes a close approach to, or landfall in, Antigua or Barbuda. Subsequent landfalls are possible Aug. 22 in other Leeward Islands, including the Caribbean Netherlands, Saint Kitts and Nevis, and Saint Croix. Afterward, Laura is expected to make landfall in eastern Puerto Rico, midday Aug. 22 followed by another landfall in the eastern Dominican Republic Aug. 23. Laura will then likely continue northwestward along the eastern Cuban coast. Afterward, as Laura reaches the open, warmer waters of the Gulf of Mexico, it will reach an environment conducive to strengthening and may become a hurricane. Long-range projections indicate there could be a further landfall somewhere along the Gulf Coast of the US around Aug. 26; however, the guidance is highly varied, suggesting low confidence forecast at this time. Significant uncertainty remains in the track and intensity forecast, and changes may occur in the coming days.

Government Advisories
As of 1700 AST Aug. 21, the following advisories have been issued in response to the storm:

 

  • Tropical Storm Warning: Puerto Rico, Vieques and Culebra, US Virgin Islands, British Virgin Islands, Saba and Saint Eustatius, Sint Maarten, Saint Martin and St. Barthelemy, Antigua, Barbuda, Saint Kitts and Nevis, Anguilla, and Montserrat; the northern coast of the Dominican Republic from Cabo Engano to the border with Haiti; and the northern coast of Haiti from Le Mole St. Nicholas to the border with the Dominican Republic

 

  • Tropical Storm Watch: Southeastern Bahamas; Turks and Caicos

 


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. The possibility of localized evacuations cannot be discounted if weather conditions prove particularly hazardous.

Hazardous Conditions
Tropical Storm Laura will likely bring heavy rainfall, strong winds, and rough seas to coastal areas across the Caribbean and southern Florida, US, in the coming days. Forecast models indicate 7.5-15 cm (3-6 inches) of rain are likely over the coming days in Puerto Rico, the US and British Virgin Islands, the Dominican Republic, the southern Haitian Peninsula, and eastern Cuba. Locally higher totals of 20 cm (8 inches) are possible on the leeward side of Cuba and Puerto Rico. Lower amounts of 2.5-7.5 cm (1-3 inches) are expected in Haiti, the northern Leeward Islands, Turks and Caicos, and southeastern Bahamas. Slight shifts in Laura's track over the coming days will affect where the heaviest rain occurs.

Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, and rivers, as well as in 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. 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.

In addition to the heavy rain, flooding, rough surf, and storm surge, Tropical Storm Laura could produce damaging wind gusts. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are possible.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions through at least Aug. 22 in the Leeward Islands and Puerto Rico; Aug. 23 in Dominican Republic and Haiti; Aug 23-24 in Cuba; and potentially beginning Aug. 26 in the US. 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. 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 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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