Two days before Helene made landfall, record-setting rains were already starting to soak the Blue Ridge Mountains in Tennessee and North Carolina. A zone of low pressure along a front pulled water vapor up from the Gulf of Mexico into the mountains, where it quickly rose, condensed into storm clouds, and dumped heavy rain.
They also created a wet, swampy environment that allowed Helene to cling to the last of its strength as it moved deep inland. Hurricanes weaken when they move over dry land - but the water vapor rising off the soaked ground in Helene's path extended the storm's life. "It's slowing its demise," Baker Perry, a professor of climatology at the University of Nevada at Reno, who previously taught at Appalachian State University said. "It's not strengthening, but it's weakening slower than it otherwise would be."
When Helene hit the mountains, it dumped all the remaining water it had collected from the Gulf of Mexico. Across the region, several months' worth of rain fell between Sept. 25 and Sept. 27.
"This was a one-in-1,000 year event across a fairly large area in terms of the three-day rainfall totals," Perry said.
Unable to soak into the saturated soil, water flowed downhill. Along the way, it picked up dirt, boulders, trees and eventually cars, homes and slabs of asphalt. Solid ground became liquid and slid away.
"Eventually things break, and it just comes down in a muddy slurry of huge boulders, huge trees, and sometimes it can be moving 35 miles per hour down the slope of the mountain," Douglas Miller, a professor of atmospheric sciences at the University of North Carolina at Asheville. said.
"In the mountains, places flooded with torrents that don't even have creeks. There was never even water there," Perry said.
Helene has become one of the deadliest hurricanes of the modern era. And now a vast operation is underway to provide relief in this difficult terrain.
It's simply sad that desperate Republicans have made hurricane relief a political issue through lies and the complete lack of recognition of just how extensive hurricane damage is. And indeed, Helene was an absolute worst case scenario that our governments and private entities combined couldn't have accurately anticipated before the rapidly developing storm hit catastrophically.Instead of Americans being informed of the thousands of dedicated workers doing their best under the most difficult of circumstances, Donald Trump and his minions instead spread vicious lies and conspiracy theories untethered to the reality on the ground, adding insult to injury for those wanting for relief workers and services to reach them in many cut-off hollows in North Carolina where roads are debris-strewn or completely washed away.