When Hurricane Florence struck the U.S. East Coast at 7:15AM ET this morning, it popped a squat near Wilmington, North Carolina. The hurricane — now downgraded to a tropical storm — is hovering over the area, unleashing torrential rainfall, and creeping towards the west at a glacial three miles per hour, according to the National Hurricane Center. That means the rain will continue to pound the same waterlogged ground — which, combined with storm surge, is leading to deadly flooding. So far, at least two people have died, according to Vox.
“Look at how slow this system is,” NHC director Ken Graham said in a Facebook Live briefing Friday morning. (When Graham talks about the storm’s speed, he means the pace at which it’s traveling, not the wind speed.) “Before that’s all said and done, it’s going to leave a wake of water, and river flooding, and a whole lot of impacts.”
We saw a similar leisurely pace with Hurricane Harvey, which dumped more than five feet of water on southeastern Texas, killing 68 people and causing so much damage that it was costlier than any hurricane except Katrina, the NHC says. So Florence’s slow speed means more danger for people in the storm’s path, as first reported by Kendra Pierre-Louis at The New York Times and Brian Resnick for Vox.
“Everything that comes with a hurricane sticks around longer,” says James Kossin, an atmospheric scientist at the National Oceanic and Atmospheric Administration. That means salt water flooding from storm surge, freshwater water flooding from rain, wind damage. “Right out of the gate, that’s not good.” Kossin’s research, published in June in the journal Nature, suggests that hurricanes have been slowing down over the past 70 years. Why? “That’s the million dollar question,” Kossin says.
In Florence’s case, there’s a high pressure system squatting to Florence’s north — which prevented Florence from moving up along the coast, and instead shunted it west onto land. That high pressure system is also exacerbating the storm’s stall. “Florence is caught between the winds wanting to blow it to the east, and that high pressure block preventing it from being blown in that direction,” says Charles Greene, a professor of Earth and Atmospheric Sciences at Cornell University. “It’s kind of stuck.”
The scientists The Verge spoke to were generally reluctant to connect the dots between Florence’s slow motion crawl through the Carolinas, and global warming. Rising global temperatures could be one explanation, but that particular link to climate change is more controversial than the links to other hurricane characteristics.