North Atlantic Ocean: Tropical Storm Gaston tracking east-southeastward near Azores, Portugal, Sept. 23 /update 2

Event

Tropical Storm Gaston is tracking east-southeastward in the central North Atlantic Ocean Sept. 23. As of 15:00 GMT, the storm's center of circulation was approximately 180 km (115 miles) north of Faial Island in the central Azores.

Forecast models indicate the system will maintain its strength as it turns to track southward and then southwestward between the western and central Azores late Sept. 23 to early Sept. 24. The storm is then expected to weaken and transition into a post-tropical cyclone as it tracks generally westward away from the Azores Sept. 24-26. The post-tropical storm will weaken further and dissipate as it turns to track southwestward Sept. 27-28. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

As of 15:00 GMT Sept. 23, 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 forecast that the most severe weather impacts in the Azores from the storm will occur late Sept. 23-early Sept. 24. The institute has issued red heavy rainfall warnings (the highest level on a three-tier scale) for the central and eastern Azores late Sept. 23-24 and yellow rainfall warnings for the western Azores Sept. 24-25. Yellow strong wind and rough seas warnings have been issued for the western Azores Sept. 23-25 and the 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 5-15 cm (2-6 inches) across the central and western Azores, with isolated higher totals. Tropical-storm-force winds are expected in the western and central Azores from Sept. 23. Swells generated by Gaston will affect the Azores through Sept. 23 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 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)