Tropical Storm Helene gained strength Wednesday and is forecast to become a hurricane later in the day as it moves into the Gulf of Mexico where the National Hurricane Center said it will intensify into a major Category 3 storm.

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, schools to close and officials to declare emergencies in Florida and Georgia.