He said that the hurricane could only be captured on a super-wide lens, even from 400 kilometres up.
People in the storm's path shared video on social media of the now-Category 1 hurricane's still-intense 90 miles per hour (150 km/h) winds as the eyewall moved through Wilmington, North Carolina.
The center downgraded Florence to a Category 1 hurricane, but warned that it still carried "very unsafe winds". "From 8 a.m.to noon, the center will drift inland across southern North Carolina, and that is when we will see the strongest winds", said WRAL meteorologist Elizabeth Gardner.
The area is expected to get about as much rain in three days as Hurricanes Dennis and Floyd dropped in two weeks in 1999.
Some 9,700 National Guard troops and civilians are now deployed, with high-water vehicles, helicopters and boats.
In all, an estimated 10 million people live in areas expected to be placed under a hurricane or storm advisory, according to the U.S. Weather Prediction Center.
Forecasters said conditions will deteriorate as the storm pushes ashore early Friday near the North Carolina-South Carolina line and makes its way slowly inland.
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.
According to the NHC's forecast discussion at 12 p.m. on September 13: "The subtropical ridge to the northeast and east of Florence is now well-established between Bermuda and the USA mid-Atlantic region and extends westward into Virginia and the central Appalachians".
And now, many more people, houses and buildings are set to endure hurricane-force winds, which extend 80 miles out from Florence's center.
Isaac, which had built to tropical storm status when its winds topped 39 mph on Saturday, has weakened to a depression over the eastern Caribbean sea with winds of 35 mph and is moving west at 15 mph, lashing the Lesser Antilles with rain squalls as of the 5 a.m. advisory.
Sheets of rain splattered against windows of a hotel before daybreak in Wilmington, where Sandie Orsa of Wilmington sat in a lobby lit by emergency lights after the electricity went out.
"You put your life at risk by staying", Cooper said.
Information from the Associated Press was used in this report. "Trees are blowing down in the wind. Nothing's hit the house yet, but it's still blowing". A city spokeswoman Colleen Roberts told WRAL-TV that 200 people have already been plucked to safety.
Antonio Ramirez, a construction worker from El Salvador living in Leland, North Carolina, said he planned to ride out the worst of the weather with his dog Canelo.
Emergency declarations were in force in Georgia, South and North Carolina, Virginia, Maryland and the District of Columbia.
More than 60 people including children had to be pulled from a collapsing motel in Jacksonville at the height of the storm, and many more who defied evacuation orders were waiting to be rescued.