South Florida is bracing for a major storm surge and powerful winds even as Hurricane Irma weakened to a Category 4 storm as it races toward the U.S. mainland. “Obviously Hurricane Irma continues to be a threat that is going to devastate the United States,” Federal Emergency Management Agency Administrator Brock Long said at a press conference Friday morning. “We’re going to have a couple rough days.”

Irma was downgraded from a Category 5 to a Category 4 storm early Friday morning. As of 8 a.m. Eastern Time, the storm was moving 16 mph and located 450 miles southeast of Miami. The National Weather Service cautioned Irma is still “extremely dangerous” with maximum sustained winds of 150 mph, which are strong enough to uproot trees, bring down power poles and rip off the roofs and some exterior walls of well-built frame homes. READ MORE