North Atlantic Ocean: Tropical Storm Gaston tracking east-northeastward Sept. 22 /update 1

Event

Tropical Storm Gaston is tracking east-northeastward in the central North Atlantic Ocean Sept. 22. As of 14:00 AZOT, the storm's center of circulation was approximately 505 km (315 miles) west-northwest of Faial Island in the central Azores.

Forecast models indicate the system will maintain its strength as it tracks east-northeastward and then east-southeastward to the north of the western Azores Sept. 22-23. The storm is then expected to weaken slightly as it turns to track south-southeastward and then southwestward late Sept. 23-early Sept. 24, tracking between the western and central Azores. The system is then expected to become post-tropical as it tracks generally westward south of Flores Island in the western Azores Sept. 24. The post-tropical storm will weaken further as it tracks first west-northwestward then west-southwestward away from the Azores Sept. 25-27. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

As of 14:00 AZOT Sept. 22, authorities have issued tropical storm warnings for Flores and Corvo islands in the western Azores and Faial, Pico, Sao Jorge, Graciosa, and Terceira islands in the central Azores. The Portuguese Institute for Sea and Atmosphere (IPMA) has issued orange heavy rainfall warnings (the middle level on a three-tier scale) over the central Azores Sept. 23 and yellow rainfall warnings over the western Azores Sept. 22, the central Azores Sept. 22-23, and the eastern Azores Sept. 23-24. Yellow strong wind warnings have been issued for the western and central Azores Sept. 23-24. Officials could issue new warnings and/or watches in response to the developing system in the coming hours.

Forecast models indicate the storm will bring rainfall accumulations of 5-10 cm (2-4 inches) across the central and western Azores, with isolated higher totals. Tropical-storm-force winds are expected in the western Azores from late Sept. 22 and in the central Azores from Sept. 23. Swells generated by Gaston will affect the Azores from late Sept. 22 and are likely to cause life-threatening surf and rip current conditions.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. Localized evacuations, flash flooding, and landslides are possible if weather conditions prove hazardous.

The inclement weather could trigger localized business, transport, and utility disruptions, rendering some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Raw sewage and other hazardous materials mixed with floodwaters pose a serious health threat.

Advice

Activate contingency plans in areas where officials forecast typhoon or tropical storm 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 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.

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
Portuguese Institute for Sea and Atmosphere (IPMA)