Caribbean Sea: Tropical Storm Ian is tracking west-northwestwards late Sept. 23 /update 1

Event

Tropical Storm Ian is tracking west-northwestward in the central Caribbean Sea late Sept. 23. As of 23:00 EDT, the storm's center of circulation was approximately 625 km (385 miles) southeast of Kingston, Jamaica.

Forecast models indicate the system will strengthen further as it gradually turns to track northwestward, passing west of Jamaica late Sept. 25. Ian is forecast to become a category 1 hurricane before making a close approach to the Cayman Islands early Sept. 26, passing just west of Grand Cayman. The system is forecast to strengthen into a Category 2 hurricane before making a further landfall over western Cuba late Sept. 26. The storm is then expected to turn north-northeastward as it crosses western Cuba and the Florida Straight through early Sept. 27 before passing over or close to the western Florida Keys late Sept. 27 and making landfall over the southwest coast of the Florida Peninsula Sept. 28. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

As of late Sept. 23, authorities have issued the following watches and warnings:

• Hurricane Watch: Cayman Islands

• Tropical Storm Watch: Jamaica

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

Forecast models predict rainfall accumulations of 10-20 cm (4-8 inches) over Jamaica and the Cayman Islands, 5-10 cm (2-4 inches) over southern Haiti and the southern Dominican Republic, and 15-25 cm (6-10 inches) over western to central Cuba. The heavy rainfall could produce flood impacts in the affected areas, including flash and urban flooding, as well as landslides over higher terrain, especially in Jamaica and Cuba. Storm surge could raise water levels by 0.3-0.9 meters (1-3 feet) above normal tide levels along the coast in the Cayman Islands late Sept. 25-26. Swells generated by the storm system will begin to affect Jamaica, the Cayman Islands, and Cuba over the coming days.

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
Jamaica Meteorological Service
Cuban Meteorological Institute
US National Weather Service