To whip up a monstrous storm like the one chugging for the Carolinas you need a handful of ingredients-warmer than normal sea temperatures; a wind pattern that allows a storm to get strong and stay strong; higher sea levels; and a storm covering an enormous area-and Florence has them all.
The slow-moving storm, with maximum sustained winds of 130 miles per hour, is expected. However, it is becoming more certain that Florence will bring a unsafe storm surge to the Carolina coast and life-threatening flooding.
While residents said they planned to stay put despite hurricane watches and warnings that include the homes of more than 5.4 million people on the East Coast, many weren't taking any chances.
When it reaches the coastline, it could sit around for days, unloading life-threatening storm surge, risky winds and flooding rain.
The storm was about 435 miles southeast of Wilmington, North Carolina and 470 miles east-southeast of Myrtle Beach, South Carolina. That funding can not be spent on disaster response, they said.
Florence is one of four named storms in the Atlantic.
"Do you want to get hit with a train or do you want to get hit with a cement truck?" said Jeff Byard, an administrator with the Federal Emergency Management Agency.
A storm as big as Hurricane Florence will hit with a "one-two punch" deluge of water, Erik Salna, the associate director of the International Hurricane Research Center at Florida International University, says.
"This will be a storm that's going to be far larger than we have seen in perhaps decades", Trump said.
Privately, you may be wondering (and you wouldn't be alone): "What exactly is storm surge?"
The National Weather Service issued an ominous warning.
Subtropical storm Joyce formed in the Atlantic on Wednesday but is not expected to threaten land.
As of Wednesday morning, 20 eastern North Carolina counties were under either a mandatory or voluntary evacuation, or some combination of the two, according to the N.C. Department of Public Safety. Second, the storm is likely to cause "life-threatening freshwater flooding from a prolonged and exceptionally heavy rainfall event" across the state, both on the coast and in the interior.
Typhoon Mangkhut is estimated to have caused $250 million worth of damage to the Phillipines with rice and corn crops bearing the brunt of the storm.
US President Donald Trump has authorised emergency measures to free up federal funds to help those responding to the storm. Cars and trucks full of people and belongings streamed inland.