Hurricane Helene struck Florida as a Category 4 storm and tore through the southeast, but saved the bulk of her devastation for an unlikely destination: the rugged mountain towns of western North Carolina.

The timing could not have been worse.

Days before Helene’s arrival, a slow-moving weather front had soaked the Blue Ridge Mountain region, delivering more than 4 inches of rain to Asheville Airport, 9 inches to Yancey County, and raising streams to record levels.

The already saturated environment yielded what the North Carolina State Climate Office called a “close to worst-case scenario.”

“As mountain streams became overrun with moisture, that water rushed down the rivers and into towns such as Asheville, all while the heaviest rain from Helene was just beginning to fall,” said Corey Davis, assistant state climatologist, in a Monday analysis.

That confluence of events helps explain the high casualty county from Helene, which brought an estimated 40 trillion gallons of rain as it beat a three-day path of destruction across the southeast United States before dissipating Sunday.

“Communities were wiped off the map,” Gov. Roy Cooper, North Carolina Democrat, said at a news conference Tuesday.

The death toll from six states rose Tuesday to 159, according to an Associated Press count, nearly half of which came from western North Carolina, located about 300 miles from the Atlantic Coast.

“We’ve seen many disasters in North Carolina from hurricanes to frost and freezes and tornadoes, but I think this probably will go down as the worst disaster we’ve seen in North Carolina,” said state Agriculture Commissioner Steve Troxler at a Tuesday press conference.

As many as 600 people are still missing or unaccounted for, but Helene’s death total has already surpassed that of such seminal 21st-century storms as Superstorm Sandy in 2012, which left 158 dead, and Hurricane Ian in 2022, which resulted in 149 deaths.

Fast-moving floodwaters and mudslides propelled down the western North Carolina mountains, wreaking devastation on the historic tourist city of Asheville and virtually wiping out the town of Chimney Rock Village.

The death toll in Buncombe County, home of Asheville, has been estimated at 40, or more than the count from the entire state of Georgia, where the total number of deaths rose Monday from 17 to 25.

Dozens of people also died in South Carolina, and deaths were reported also in Florida, Tennessee and Virginia.

One factor making it difficult to get an accurate death toll is the damage to communications in remote regions.

“In fact, communication has been difficult in a number of areas, if not impossible,” Homeland Security Secretary Alejandro Mayorkas said Tuesday in a White House briefing.

Eastern North Carolina’s beachfront and coastal communities grappled with their share of hurricanes, including Florence in 2018, Matthew in 2016, and Floyd in 1999, but not the western mountains.

“This really is unprecedented here,” said Rep. David Rouzer, North Carolina Republican. “This would be the equivalent, at least in my mind, of 50 inches of snow at Wrightsville Beach. I mean, how do you prepare for that? There is no way to prepare for that.”

Mr. Cooper said Tuesday that President Biden “gave the green light” to use U.S. military forces soon, citing, among other things, the extensive damage to water systems in the region.

More than two dozen plants were not producing water Tuesday, and Asheville city officials are warning that normal service is likely weeks away because both pipes and treatment facilities have been badly damaged.

“We know that this crisis will likely be a sustained crisis because of water system issues,” Mr. Cooper said.

Rep. Greg Murphy, North Carolina Republican, said there’s no comparison between storms that result in flooding along the Eastern coast versus flooding in the Western mountains.

“Here in the mountains, it comes down slopes. You have gully washers, you have flash floods with so much of a higher velocity, which we’ve seen from the air,” Mr. Murphy said. “Tragically, it has taken out villages and homes alike.”

Although Helene came ashore in Florida, that state has essentially completed its own relief efforts and is now helping out neighbors less used to handling hurricanes.

Gov. Ron DeSantis told reporters Tuesday that Florida has sent emergency resources, including members of its National Guard and its transportation and emergency management departments, to North Carolina and Tennessee.

“Just yesterday, a joint Florida State Guard and Florida Fish and Wildlife Commission team rescued a mother and her 1-year-old infant,” Mr. DeSantis said, adding that food and bridge-building teams are also on their way.

The tiny town of Busick in Yancey County topped the list with 31.33 inches of rain, while Mount Mitchell received more than two feet and Asheville was soaked by 14 inches of rain, state weather officials said.

The North Carolina Department of Transportation said drivers should “consider roads in western North Carolina to be closed and avoid travel unless it is absolutely necessary” while 1,600 state workers and crews move to clear debris and block off roads destroyed by flooding.

Where cars cannot pass, however, mules can. The Mountain Mule Packer Ranch delivered trailers loaded with donated supplies, including insulin and diapers, to a staging area in western North Carolina, as shown on its Facebook page.

Mr. Biden is scheduled to take an aerial tour Wednesday of the damage in South Carolina and western North Carolina.

Frank Matranga, a representative from the Federal Emergency Management Agency, told reporters that more than 150,000 households have registered for assistance, a number that the agency expects to “rapidly increase over the coming days.”

He said the federal government has deployed 1,250 urban search-and-rescue personnel, 1.9 million ready-to-eat meals, more than 1 million liters of water, 95,000 tarps, and 150 ambulances.

“This is, without a doubt, a widespread and extraordinarily devastating disaster,” Mr. Matranga said. “We’re here to support the response across all of the affected states and do that with empathy and sensitivity. We’re committed to being there every step of the way, and it’s going to be a long way.”

Sen. Thom Tillis, North Carolina Republican, said, “We’ve got to be prepared to be in this for the long haul.”

“Time and time again, after we’ve had hurricane and flooding events, the people of western North Carolina have come to our aid,” said Mr. Murphy, “and now it’s time for the rest of the state to come to western North Carolina’s aid.”

• This article is based in part on wire service reports.

• Valerie Richardson can be reached at vrichardson@washingtontimes.com.