North Atlantic Ocean: Tropical Storm Henri tracking westward in the North Atlantic Ocean early Aug. 19 /update 4

Event

Tropical Storm Henri is tracking westward in the North Atlantic Ocean early Aug 19. As of 05:00 AST Aug. 19, the storm's center of circulation was approximately 845 km (525 miles) southeast of Cape Hatteras, North Carolina. Forecast models indicate the system will maintain its strength as it continues tracking west through early Aug. 20. Henri is forecast to turn northwest then north while strengthening into a category one hurricane by early Aug. 21. The storm is likely to continue tracking north across the North Atlantic Ocean, towards Massachusetts through at least Aug. 22 before weakening into a tropical storm and making a close approach to Nantucket, Massachusetts, US, early Aug. 23. After the close approach, Henri will turn to track northeast, moving away from Massachusetts, early Aug. 24. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

Government Advisories
No warnings or watches are in effect. Officials could issue new warnings and/or watches in response to the developing system in the coming days.

Hazardous Conditions
The storm may bring heavy rainfall at times, gusty winds, and rough seas to Bermuda through at least Aug. 19. Sustained heavy rainfall could trigger flooding in low-lying communities and urban areas with easily overwhelmed stormwater drainage systems. Torrential precipitation could trigger flash floods and mudslides.

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. Swells generated by Henri could affect Bermuda through at least Aug. 20 and could affect the southeast and mid-Atlantic US coasts from Aug. 21. In addition to the potential 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. Floodwaters and debris flows could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion. Possible 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 weather 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 weather conditions. Heed any evacuation orders that may be issued. 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 and necessary medications 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.

Resources

US National Hurricane Center
National Weather Service
Bermuda Weather Service