(CBS Local) – A National Weather Service satellite monitoring Hurricane Florence has recorded a wave reaching 83 feet in the storm churning in the Atlantic Ocean.

That’s more than eight stories tall, for reference.

A satellite altimeter under the northeast quadrant, the strongest area of the storm, recorded the wave. It ranged 59 to 83 feet Wednesday morning.

The waves are produced by being trapped along with incredibly strong winds moving in the same direction as the storm’s motion.

Hurricane Florence’s leading edge battered the Carolina coast Thursday, bending trees and shooting frothy sea water over streets on the Outer Banks, as the hulking storm closed in with 105 mph (165 kph) winds for a drenching siege that could last all weekend.

Forecasters said conditions will only get more lethal as the storm pushes ashore early Friday near the North Carolina-South Carolina line and makes its way slowly inland. Its surge of ocean water could cover all but a sliver of the Carolina coast under as much as 13 feet, and days of downpours could unload more than 3 feet of rain, touching off severe flooding.

Florence’s winds weakened as it drew closer to land, dropping from a peak of 140 mph (225 kph) earlier in the week, and the hurricane was downgraded from a terrifying Category 4 to a 2.

But North Carolina Gov. Roy Cooper warned: “Don’t relax, don’t get complacent. Stay on guard. This is a powerful storm that can kill. Today the threat becomes a reality.”

Forecasters said that given the storm’s size and sluggish track, it could cause epic damage akin to what the Houston area saw during Hurricane Harvey just over a year ago, with floodwaters swamping homes and businesses and washing over industrial waste sites and hog-manure ponds.

“It truly is really about the whole size of this storm,” National Hurricane Center Director Ken Graham said. “The larger and the slower the storm is, the greater the threat and the impact — and we have that.”

Schools and businesses closed as far south as Georgia, airlines canceled about 1,200 flights and counting, and coastal towns in the Carolinas were largely emptied out.

Around midday, Spanish moss blew sideways in the trees as the winds increased in Wilmington, and floating docks bounced atop swells at Morehead City. Some of the few people still left in Nags Head on the Outer Banks took photos of angry waves topped with white froth. By early afternoon, utilities reported about 12,000 homes and businesses had lost power.

Wilmington resident Julie Terrell was plenty concerned after walking to breakfast past a row of shops fortified with boards, sandbags and hurricane shutters.

“On a scale of 1 to 10, I’m probably a 7” in terms of worry, she said. “Because it’s Mother Nature. You can’t predict.”

More than 1.7 million people in the Carolinas and Virginia were warned to evacuate over the past few days, and the homes of about 10 million were under watches or warnings for the hurricane or tropical storm conditions.

© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.