(CNN) - Even by major hurricane standards, Florence is a beast like no other.
The National Weather Service calls it a "storm of a lifetime" -- and for good reason.
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A perfect storm of unfortunate circumstances means Florence will likely be catastrophic for parts of the Southeast. Here's what makes this hurricane so unusual:
1. Its marathon attack
Around the same time Florence makes landfall, the steering winds pushing it forward will die down. In other words, this hurricane will basically stall -- pounding the same parts of the Carolinas over and over again.
From late Thursday through early Sunday, Florence will travel "literally slower than a walking pace (2 to 3 mph on average)," CNN meteorologist Brandon Miller said.
As a result, the coastal Carolinas will suffer more than 24 hours of hurricane-force winds and storm surge, CNN meteorologist Dave Hennen said.
This kind of long-term attack portends severe destruction. While a fast-traveling hurricane might blow off some shingles, a relentless onslaught such as this could easily blow off roofs or destroy houses.
"It's cumulative damage," CNN meteorologist Chad Myers said. "If you're blowing 100 or 120 mph on homes, they're going to start to deteriorate. So will the trees. So will the power lines, as the trees fall down."
2. The span of its hurricane-force winds
The area covered by Florence's hurricane-force winds has doubled -- meaning far more people will get blasted with winds 74 mph or greater.
On Tuesday, hurricane-force winds stretched 40 miles out from the center, Miller said. But by Thursday morning, hurricane-force winds extended 80 miles beyond the center of Florence.
"This means more people, structures and land will be subject to the dangerous winds," Miller said.
3. The deadly walls of water
But astonishing winds aren't the biggest danger. That would actually be Florence's storm surge, the Federal Emergency Management Agency said.
"Storm surge has the highest potential to kill the most amount of people," FEMA Administrator Brock Long said. "It also has the highest potential to cause the most destruction."
Storm surge is basically a wall of seawater that could fall on and swallow parts of the coast.
"This will have a storm surge in the 20-foot range," Myers said.
To put things in perspective, any storm surge taller than 12 feet is "life-threatening," National Hurricane Center Director Ken Graham said.
And no one knows how far inland that coastal flooding will spread, or how many inland communities will be washed out.
"The forecast shows a storm surge higher than many homes," North Carolina Gov. Roy Cooper said. "From the storm surge alone, tens of thousands of structures are expected to be flooded in North Carolina."
4. It will cause massive inland flooding
Aside from the storm surge and coastal flooding, expect colossal freshwater flooding as well. That's because the longer this slow-moving hurricane hovers over land, the more rain it'll dump in the same places.
"With this storm, what's unique is it's forecast to stall ... dropping copious amounts of rainfall across the Carolinas and into Virginia," Long said. "So this is not just going to be a coastal threat. It's a statewide threat for the states involved."
Florence will unload up to 40 inches of rain in parts of North Carolina. By comparison, Washington, D.C., gets an average of 40 inches of rain per year.
What's worse: Much of the Carolinas are already saturated from rainfall. So the land can't absorb much more water.
"Inland flooding will be a major threat and something people far from the landfall location should be concerned about," Miller said.
5. It's barreling toward people not used to big hurricanes
The Carolinas will likely bear the brunt of Florence's wrath. But that part of the East Coast rarely sees major hurricanes.
And in the 29 years since Hurricane Hugo struck, the population of the coastal Carolinas has skyrocketed.
"There's 25% more people living between Charleston (South Carolina) and Morehead City (North Carolina) than there were when Hugo was making landfall," Myers said.
"Many of the people here have never seen a storm this strong. ... They have no idea what 'overwash' of an island will do to a home, what the wind could do to your home and what to do to your home to make it safer after you evacuate."
Even Wilmington, North Carolina -- a coastal city accustomed to severe weather -- is bracing for an unusually brutal impact.
"We're a resilient bunch down here. We go through a lot of these hurricane scares throughout the years," Wilmington Mayor Bill Saffo said. "But this is pretty serious."
He warned residents to take precautions "because once this storm is upon us, we're not going to be able to send emergency personnel out to rescue you."