Tropical Storm Helene formed in the northwestern Caribbean Sea, threatening to hit as the strongest storm to make landfall in the US in over a year.
Helene is expected to rapidly intensify over the warm waters of the Gulf of Mexico, potentially becoming a Category 3 major hurricane in just 48 hours.
A hurricane warning was issued for parts of Florida's Gulf Coast, from Anclote River to Mexico Beach, with the Mexican government also issuing a warning from Cabo Catoche to Tulum.
Evacuations began Tuesday for some coastal areas of Florida facing potentially dangerous storm surge, with mandatory evacuations ordered in parts of at least seven counties.
The Big Bend area faces the most serious storm surge risk, with up to 15 feet of surge possible, and multiple feet of surge expected in areas farther south.
Florida Gov. Ron DeSantis expanded an emergency declaration from 41 to 61 counties, helping expedite preparations and coordination between the state and local governments.
Tropical storm-force wind gusts could begin as early as Wednesday afternoon, with hurricane-force wind gusts possible for many coastal areas, and heavy rainfall expected for much of the Southeast.
A level 3 of 4 risk of flooding rain is in place for parts of Florida, Georgia, Alabama, and the Carolinas, with widespread rainfall totals of 4 to 8 inches expected.
Residents are urged to prepare for damaging winds, flooding rainfall, and potentially life-threatening storm surge, with officials warning that time is running out to prepare for the storm.