Tropical Storm Helene was rapidly strengthening in the Caribbean Sea and expected to become a hurricane Wednesday while moving north along Mexico's coast toward the U.S., prompting residents to evacuate,

Helene was expected to strengthen into a hurricane on Wednesday, and it could become a major hurricane before it arrives on Florida's Gulf Coast as soon as late Thursday. The storm was 145 miles (235 kilometers) south of the western tip of Cuba, had sustained winds of 60 mph (95 kph) and was moving northwest at 12 mph (19 kph).

Forecasters say they expect Tropical Storm Helene in the Caribbean Sea to strengthen rapidly and become a hurricane as it moves north across the Gulf of Mexico on Wednesday toward the U.S. The National Hurricane Center has issued hurricane warnings for northwestern Florida’s coastline and part of Mexico’s Yucatan Peninsula.