Florida is bracing for what could be the United States’ heaviest-hitting hurricane so far this season, as an area of thunderstorms builds strength in the Caribbean Sea before potentially bringing life-threatening storm surge and hurricane-force winds to the Southeast later this week.

Tampa Bay area residents should prepare for potential hurricane conditions on Thursday, officials say, with Tropical Storm Helene expected to become a hurricane in the Gulf of Mexico later today. A stretch from Pasco County north along the Big Bend to Mexico Beach in the Panhandle is under a hurricane warning.