Hurricane Helene made landfall Thursday in northwestern Florida as a Category 4 storm as forecasters warned of “catastrophic” flooding along the Gulf Coast.

The National Hurricane Center in Miami said Helene roared ashore around 11:10 p.m. EDT and near the mouth of the Aucilla River in the Big Bend area of Florida’s Gulf Coast. It had maximum sustained winds estimated at 140 mph.

Officials have forecast storm surges of up to 20 feet and warned they could be particularly “catastrophic and unsurvivable” in Florida’s Apalachee Bay.

Hurricane warnings and flash flood warnings extended far beyond the coast up into northern Georgia and western North Carolina.