It's huge, it's dangerous, and it's going to hit.
Barring a meteorological miracle, Hurricane Florence is on track to make landfall on the US east coast somewhere along South or North Carolina around Friday morning Australian time.
It's packing winds of more than 200 kilometres an hour, and forecasters warn it threatens to create a storm surge that in some places will reach 4 metres high.
That's easily enough to overwhelm many low-lying islands and beachfront areas.
While all that sounds bad, and it is, it may not be the worst of it.
Rain, rain and more rain
Because the hurricane has travelled over warmer-than-usual ocean, it has accumulated vast volumes of moisture. And that means rain. Massive amounts.
It's not the coast that could suffer the most, said Federal Emergency Management Agency spokesman Steve Goldstein.
"Once the storm does move inland, the inland flooding threat is extreme," he said.
"Fifteen to 25 inches of rain is forecast, with up to 40 inches near the exact centre of Florence."
By some calculations, more than a metre of rain could fall in places. A metre!
That's up to an adult's waist, across huge areas of already-waterlogged land.
But even if it's "just" 30, 40 or 50 centimetres, that means serious flooding.
And unfortunately, the US has recent history with devastating inundation of cities and farms.
Hurricane Harvey virtually stopped over Houston
In August last year, Hurricane Harvey smashed into the Gulf State of Texas.
The winds and storm surge caused huge damage to coastal communities, but it was the flooding that created the greatest problems.
Like Florence, Harvey came laden with moisture. And instead of tracking quickly over the state, it virtually stopped over the Houston area.
For several days the torrential rain simply didn't stop. In some areas, well over a metre of rain was dumped on flat land with limited drainage.
As a consequence, large areas of Houston went under. Entire suburbs were submerged. Rescue services were overwhelmed.
Civilians formed the "Cajun navy", a flotilla of privately owned boats that saved thousands of people from their rooftops, their flooded cars and farms.
It cost the nation around $US170 billion, making it the country's second most costly hurricane.
Florence could be a repeat of Harvey
Now, meteorologists are predicting Hurricane Florence could see a repeat of the Harvey experience.
Like Harvey, Florence is likely to hit the coast as a category 4 storm, carrying incredible amounts of moisture.
And a blocking high, or a high-pressure system, is sitting to the north and could slow the progress of Florence right down.
The more time it sits over an area, the greater the danger of catastrophic flooding. Even well inland, boats may be the most valuable means of transport.
That's what's got so many governors and mayors warning their people not to be complacent, and that Florence is a life-threatening storm.
"I know folks have been watching the weather reports over the last few days and thinking well, we might just dodge this bullet," said Charleston Mayor John Tecklenburg.
"Well, now is the time to make that decision to go ahead and get out of town."
"It's going to be a lousy weekend here and it's going to be a good weekend to be somewhere else," he said.
Some are choosing to ignore the evacuation orders, like Casey Dodson, who said he was planning to ride out the storm.
"I'm not even worried at all," he said.
"We've got all the windows boarded up, and just faith in God we're going to be here when its all over."
Let's hope his uber optimism is rewarded. But the National Weather Service has warned the effect of this storm will be "unprecedented".
"This will likely be the storm of a lifetime for portions of the Carolina coast."ABC