Helene strengthened into a Category 4 hurricane hours ahead of its expected landfall on Florida’s northwest coast Thursday night, and forecasters warned that the enormous storm could create a “nightmare” surge in coastal areas and bring dangerous winds and rain across much of the southeastern U.

Helene has strengthened into a hurricane with forecasters warning that the storm would intensify as it crosses the Gulf of Mexico on a path to Florida.

What can a storm the size of Helene do to Florida? A Cat 3 hurricane, as Helene is forecast to be when it makes landfall somewhere near the Panhandle, can be strong enough to blow in the door of a building or rip the siding from a house.