Caribbean: Tropical Depression Six tracking west-northwestwards in the Martinique Passage Aug. 9

Event

Tropical Depression Six is tracking west-northwestwards in the Martinique Passage Aug. 9. As of 23:00 AST, the storm's center of circulation was approximately 64 km (40 miles) east-southeast of Dominica. Forecast models indicate the system will strengthen slightly and likely make landfall over Dominica as a tropical storm, early Aug. 10. The storm is forecast to continue strengthening and track northwestwards across the Caribbean Sea through Aug. 10 before making a second landfall over southwestern Puerto Rico late Aug. 10, and a third landfall over the eastern Dominican Republic early Aug. 11. After landfall, the storm will gradually weaken as it tracks northwestwards across the Dominican Republic Aug. 11 and exit into the North Atlantic Ocean later that day. The storm will likely maintain its intensity and track northwestwards in the North Atlantic Ocean, along the coast of Cuba through Aug. 13. The system is forecast to turn north-northwest and make another landfall as a tropical storm near Marathon, Florida State, US early Aug. 14, and track across the Gulf of Mexico through Aug. 14. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

Government Advisories

As of 23:00 AST Aug. 9, the following warnings and watches are in effect:

• Tropical Storm Warning: Puerto Rico, including Culebra and Vieques; US Virgin Islands; the Dominican Republic, south coast from Punta Palenque eastward as well as on the north coast from Cabo Frances Viejo eastward

• Tropical Storm Watch: Martinique; Guadeloupe; Dominica; Saba; Sint Eustatius; Dominican Republic, on the north coast from Cabo Frances Viejo to the Dominican Republic/Haiti border; Haiti, from the northern border with the Dominican Republic to Gonaives

Officials could issue new warnings and/or watches in response to the developing system in the coming hours.

Hazardous Conditions
The storm will likely bring heavy rainfall, strong winds, and rough seas to coastal areas in the Caribbean through at least Aug. 12. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and 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. Forecast models indicate 5-10 cm (2-4 inches) of rainfall are likely over portions of the Leeward Islands, Virgin Islands, and Puerto Rico. Models also indicate 1.5-8 cm (1-3 inches) of rainfall over the northern Windward Islands and 8-16 cm (3-6 inches) of rainfall over the Dominican Republic through at least Aug. 11. Flooding could trigger flash floods and mudslides, isolating some communities for several days.

Prolonged sea swells and storm surge generated by the system may result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments. In addition to the heavy rain, flooding, and storm surge, the storm could produce damaging wind gusts, resulting in power outages due to fallen trees and toppled utility lines.

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. 12 in coastal areas of the Leeward Islands, Virgin Islands, and Puerto Rico. 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 adverse 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 days. 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.

Resources

US National Hurricane Center
National Weather Service
Barbados Meteorological Services
Cuba Instituto de Meteorologia (Spanish)
Dominican Republic Oficina Nacional de Meteorologia (Spanish)
Dominica Meteorological Service
Haiti Centre national de meteorologie (French)
Meteo-France (French)
Saint Lucia Meteorological Services
Saint Vincent and the Grenadines