Tropical storm force winds began battering Florida on Thursday as Hurricane Helene was poised to make landfall, with forecasters warning that the enormous storm could create a “nightmare” surge along the coast and churn up damaging winds hundreds of miles inland across much of the southeastern U.

Hurricane Helene was upgraded to a Category 2 storm Thursday and expected to grow even stronger before making landfall in Florida’s Big Bend region on Thursday evening. Nearly 300 miles of the Florida coastline — from Mexico Beach in the Panhandle to the Anclote River just north of Tampa — was under a hurricane warning.