Caribbean Sea: Tropical Storm Ian tracking northwestward late Sept. 25 /update 3

Event

Tropical Storm Ian is tracking northwestward in the western Caribbean Sea late Sept. 25. As of 23:00 EDT, the storm's center of circulation was approximately 225 km (140 miles) south of Grand Cayman, Cayman Islands.

Forecast models indicate the system will intensify into a Category 1 hurricane before its close approach to the Cayman Islands early Sept. 26, passing west of Grand Cayman. The storm will strengthen further into a Category 2 hurricane before making landfall over far western Cuba early Sept. 27. Ian is forecast to turn northward as it crosses western Cuba, potentially strengthening into a Category 4 hurricane over the Gulf of Mexico by early Sept. 28. The system will likely weaken into a Category 1 hurricane before landfall over North Central Florida late Sept. 29. Ian will weaken further after landfall as it tracks northward across Florida and southern Georgia through Sept. 30. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

As of late Sept. 25, authorities have issued the following watches and warnings:

• Hurricane Warning: Grand Cayman; the Cuban provinces of Isla de Juventud, Pinar del Rio, and Artemisa

• Tropical Storm Warning: Cuban provinces of La Habana, Mayabeque, and Matanzas; Lower Florida Keys from Seven Mile Bridge westward to Key West; Dry Tortugas

• Tropical Storm Watch: Little Cayman and Cayman Brac; Englewood southward to Chokoloskee

• Storm Surge Watch: the Florida Keys from the Card Sound Bridge westward to Key West; Dry Tortugas; West coast of Florida from Englewood southward to the Card Sound Bridge; Florida Bay

Officials could issue new warnings and/or watches in response to the developing system in the coming hours. Authorities in the US issued an emergency declaration for Florida Sept. 24 in advance of the storm.

Forecast models predict additional rainfall of 2.5-7.5 cm (1-3 inches) over Jamaica. Rainfall accumulations of 15-25 cm (6-10 inches) over western Cuba, 7.5-15 cm (3-6 inches) over the Cayman Islands, and 5-10 cm (2-4 inches) over the Florida Keys into southern and central Florida Peninsula are possible. Heavy rainfall may affect North Florida, the Florida Panhandle, and portions of the Southeast Sept. 29-Oct. 1. 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. Flash and urban flooding may occur across the Florida Keys and Florida peninsula through Sept. 28, while flooding and river level rises are possible across northern and central Florida and parts of the Southeast through Sept. 30 due to the already saturated antecedent conditions.

Storm surge could raise water levels by 2.7-4.3 meters (9-14 feet) above normal tide levels along the coast of western Cuba late Sept. 26-early Sept. 27. Storm surge in Florida could raise water levels above normal tide levels by 1.2-2 meters (4-7 feet) from Englewood to Bonita Beach, 0.9-1.5 meters (3-5 feet) from Bonita Beach to East Cape Sable, and 0.6-1.2 meters (2-4 feet) from East Cape Sable to Card Sound Bridge including Florida Bay and the Florida Keys including the Dry Tortugas. Swells generated by the storm system are affecting Jamaica and the Cayman Islands; they will probably spread northwestward to the southwestern coast of Cuba and the coasts of Honduras, Belize, and the Yucatan Peninsula of Mexico Sept. 26. Reports indicate damage to two houses in Portland, Jamaica.

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