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,

Tropical Storm Helene formed in the Caribbean on Tuesday and could become Hurricane Helene before it strikes Florida later this week.

Tropical Storm Helene formed Tuesday in the Caribbean Sea and could strengthen into a major hurricane while moving north toward the U.S., forecasters said.