Why Helene is going to be so bad in western North Carolina

A hurricane that formed in the Gulf of Mexico is barrelling north towards the mountains, where catastrophic flooding is likely to happen. So we asked a meteorologist why this storm will hit so hard.

A satellite image of Hurricane Helene moving into the Gulf of Mexico taken by NOAA's GOES-16 (GOES East) satellite at 3:51 pm (ET) on Sept. 25, 2024. (Image credit: NOAA)

UPDATE (9/27/24, 2:33p): I’d planned on creating a live blog or posting updates on Helene, but it’s been pretty hard to keep up. I’m posting what I’m seeing over on Twitter, and I’d encourage you to keep up with local media accounts, or official National Weather Service posts.

---

Here’s a note on a NOAA press release that explains just how bad Hurricane Helene will likely be in the mountains:

UPDATED: September 25, 2024. Reporters: This is a rare news release from NOAA for an operational weather event. We urge the news media to continue focusing the public’s attention on the major impacts from inland flooding expected along the path of Helene well after landfall.

I’ve seen thousands of press releases over the course of my career. I have never really seen one from a government agency that basically says “Reporters: Do NOT get this story wrong.”

As of right now, at 3 or so on Thursday afternoon, Helene has not made landfall. But the National Weather Service is not messing around. Here’s a statement out this afternoon from the NWS office in Greenville-Spartanburg:

This will be one of the most significant weather events to happen in the western portions of the area in the modern era. Record flooding is forecasted and has been compared to the floods of 1916 in the Asheville area.

It goes on:

We plead with everyone that you take every single weather warning very seriously through the entirety of this event as impacts will be life-threatening and make sure to have to have multiple ways to receive the alerts … We cannot stress the significance of this event enough.

To wit, the 1916 Asheville flood breached dams, left 80 people dead, destroyed railroad lines, and cut the city off from the outside world. On the 100th anniversary of the flood in 2016, the city of Asheville itself took a look back at what would likely happen if a similar storm rolled through the mountains in modern day. “Based on both history and future meteorology modeling,” the story concluded, “it will.”

Asheville, NC, railroad yard, 1916 flood (likely July 1916). From the General Negative Collection, North Carolina State Archives.

This is not intended to be a live blog or a comprehensive update on the storm, although I’ll try to add more information to the bottom of the web version of this story as I can. But I did want to figure out what exactly makes Hurricane Helene so dangerous, so I called up WFMY News 2 chief meteorologist (and friend of the Rabbit Hole) Tim Buckley to have him explain this and other recent storms in terms that non-meteorologists can understand. His answers below have been edited for clarity and brevity:

RABBIT HOLE: This storm feels different. So how different is it?

TIM BUCKLEY, WFMY meteorologist: It's a good question. This storm is affecting North Carolina in a pretty big way, but it's not affecting it in the usual way. Number one: It's coming from the Gulf of Mexico. We get storms that come in from the Gulf pretty often. But with this one, you have all of this flooding rain that's spreading out ahead of it before it even gets here. And that's part of a second system that's more or less a cold front or a stationary front. It's just tugging up and sucking up all of this moisture into the mountains. So they've already been getting rain since Wednesday. They're gonna get all that before the storm even gets there.

RABBIT HOLE: Is it just me, or are more storms forming in the Caribbean like this one?

BUCKLEY: I don't think we have the numbers to say that more storms are forming in the Caribbean. One thing we can say about this season so far is that we really haven't had those storms forming way way out closer to Africa like we usually do. There's something weird going on there. Hurricanes usually form with thunderstorms that come off of Africa. For some reason, the band of storms that come off Africa have actually shifted north. So it's been one of the wettest summers on record for parts of the Sahara Desert which, I know, sounds just insane to say. But the storms are coming off at a weird entry point to the Atlantic where it's a little too cold for them to get going. That's thrown that part of the equation a little bit out of whack. We're in the weeds here, but that's kind of the why as far as those big long-lived Atlantic ones haven't been happening this year. (NOTE: The Charleston Post and Courier sent two reporters to West Africa to take a closer look at what’s going on over there.)

I do want to say: I don't think that this is going to necessarily be a long-term trend. We could still have some more traditional Atlantic hurricanes this year, and I'm sure we'll continue to have them in the future.

RABBIT HOLE: Is there anything different about the track of a storm that comes through that traditional Atlantic path versus something that forms in the Caribbean?

BUCKLEY: There are a couple of main differences. Number one: When they're forming in the Gulf or in the Caribbean, they're closer to home. They could go from nothing to a big one in one or two days. As we're talking right now: Helene was a tropical storm yesterday. Today, it’s a Category 3 hurricane, which is considered a major hurricane. That's the biggest difference.

RABBIT HOLE: Is that because the water in the Gulf is warmer?

BUCKLEY: The Gulf almost always has the warmest water available in the ocean, warmer than the water out in the open Atlantic. Not only are you forming a storm really quickly, but it has all the octane and all the fuel available to get really strong, really fast. The ocean waters are setting records. The Atlantic and the Gulf have been as warm as ever, if not warmer. So the heat in the oceans is off the charts.

It gives people less time to prepare. Because even if you forecasted a storm perfectly, you're telling people to prepare for something they can't see. So if you're saying, Hey, there's a cat four hurricane coming your way and they turn on the Weather Channel and it's still a tropical storm, it's hard for them to believe that, even though it might only be 36 hours away. And so if you're in Tallahassee, you really have to take action based on a forecast, which is harder to do than when you see it for yourself.

RABBIT HOLE: Helene seems like it’s moving fast. How does that play into what’s going to happen in the mountains?

BUCKLEY: Yeah, it’s moving pretty fast. That’s usually a good thing when it comes to rainfall. If you can get it in and get it out, usually you don't get as much rain. We saw with Debby earlier this year that when a storm sits for days, it rains and rains and rains and rains.

The thing that makes it unusual is what's already been going on in the mountains. We've had days of rainfall before the storm gets here. That’s something that is a little unrelated to Helene. So we have this weather system that's already there ahead of it. Think of it like a big vacuum. There's a front there by the mountains that's acting like suction. It’s taking off moisture from the tropics and from the Gulf and partially related to Helene, it's already been sucking it up for a couple of days. So it started raining there Tuesday, Wednesday, and now Thursday into Friday. And so before Helene even gets there, they're already going to have more than 10 inches in parts of the mountains, and then they’ll get more. It’s unusual to have a pre-event.

It just sets the stage really badly because if you think of the ground like a sponge, everything is going to be already saturated. And then you're gonna have a hurricane on top of that. That's not normal. So to me, that’s the biggest thing that's unusual about this one. It isn't necessarily the speed, but it's the fact that there's already so much rain happening before the storm that's going to make it really a bad flood disaster for western North Carolina.

Rainfall forecast from the National Weather service as of noon Thursday.

RABBIT HOLE: You've been here for a long time covering all kinds of storms in North Carolina. What are the big differences between a hurricane that hits in eastern North Carolina versus the mountains?

BUCKLEY: From a North Carolina perspective, hurricanes that form in the Caribbean or the Gulf are worse for the mountains. The ones that are in the Atlantic are worse for the beaches.

Maybe we could use the example of Carolina Beach, which got 20 inches of rain from an unnamed storm last week. Now the Asheville area might get 20 inches of rain. What's the difference between the two? They're both really bad. But obviously the coast is flat as a pancake. It’s mostly sandy and mostly able to absorb a good amount of the water. Now, anybody that gets 20 inches of rain is gonna have a huge problem on their hands. But if you do that in the mountains, you are dropping that on slopes which funnel the water into valleys, and they make the flooding so much worse. So, terrain and topography, it makes a bigger mess of flooding whenever you get heavy rainfall, let alone from a hurricane. And so with this one, I expect you're gonna have a lot of valleys and towns that just have horrible flooding. You're probably gonna have roads that wash out. You're going to have landslides and and mudslides.

Also, the elevation plays a big deal in what kind of wind you're gonna see. I mean, we could see hurricane-force winds on tops of the peaks out there, like Mount Mitchell and, and the Balsams and the others out that way. They could see winds well over 70 or 80 miles-per-hour.

RABBIT HOLE: Is that because there's literally less in the way, so you’re getting more powerful winds at that elevation?

BUCKLEY: There's less in the way, but the mountains actually stick up into a different part of the atmosphere. If you're 6,000 feet above the ground, you're actually in a different level of the atmosphere at that point. The winds are just just in a stronger part of the storm.

RABBIT HOLE: Is there other good context to have when you're talking about hurricanes or tropical storms in general?

BUCKLEY: One thing that's been causing me to pull my hair out a little bit is the hurricane cone. Everybody in North Carolina knows what the hurricane cone is. Not everybody knows what it really means. The hurricane cone is trying to tell you where the center of the storm is gonna go. It does not tell you how big the storm is, and it doesn't tell you where it's gonna be windy or rainy. It doesn’t tell you about tornadoes or anything like that. So, in this particular case, there have been many days where the cone has basically been entirely out of North Carolina. You might look at the image and say, well, we're good. But if you check up with a meteorologist, the Weather Service, or any of your local sources, they'll tell you differently.

In this case, the hurricane is hundreds of miles wide and the east side of the storm is the bad one that has more wind and threat for tornadoes and rain and all of those things. Everybody in North Carolina is going to get some impact from the storm, whether it's a little bit or a lot of rain. Everybody in the state has a tornado threat tomorrow. The impacts extend way beyond the cone. And so I don't think people get that.

The National Hurricane Center’s “cone” forecast from noon Thursday, showing the likely path of Helene’s center.

That's kind of been hard for us to explain because the unique part about Helene is that the center is gonna be really far west of us and it's gonna be way, way out there, maybe clipping western part of the state, say, in Murphy. If you're in Manteo, why would I care? Well, you're still gonna have a tornado threat. You're still gonna have gusty winds. Um, so this one has more size to it than usual in terms of wind rain and the tornado threat and that's definitely been a challenge to get people to take seriously, for sure.

RABBIT HOLE: So I think you and a lot of people are about to be inundated with pictures, reports, videos, all kinds of things from this storm. But there’s something that I call the “Boone Mall” problem. As in: You can show flooding from the Boone Mall parking lot and it looks bad, but people in Boone are like “that floods all the time.” So, how can you tell what’s unusual, what’s real, and what’s important? Like, what’s signal and what’s noise?

BUCKLEY: I'm here in Greensboro and if there are a couple showers, Latham Park floods, right? People that live in the area know that. So it's really good to have local sources that you can seek out or find when it comes to this stuff. For the Asheville area, I'm not an expert on what kind of flooding they're experiencing out there. I've gathered that the Biltmore Village tends to flood quite a bit. That seems like it's already been happening. So it's good to try and find a local source that can put it into some perspective for you.

One of the things that I'm gonna be using is river gauges from the National Weather Service. Not only will they show you if this a minor flood or a major flood, but they have record crests from history. And unfortunately, right now, the French Broad River out by Asheville is forecast to be toward record levels. This could rival some of the worst floods that they've had before. So comparing it to history is good, seeking out some locals that might know better is good.

The other issues we have to deal with is trying to make sure the pictures are actually real nowadays. Uh You have to watch out for AI stuff or other pictures that people want to go viral. So this time of year, if you're looking at a picture and it looks like bad damage, ask yourself: Are there leaves on the trees? Is it the right time of the year? Is it in Kansas or is it in North Carolina? We've always been looking out for those type of things, but you have to do that a little bit more now.

But for this event, I fully expect it's going to be one of the worst floods in North Carolina Mountain history. We don't know how it'll rank just yet. But the forecasts are as bad as anything. With the duration of the event and the amount of water, it's going to have a long-lasting impact out that way. I've been telling people: Don't go there. A lot of people have plans. It's the fall season. I’ve been like: Don't even think about going there until the storm is over. They closed the Blue Ridge Parkway for a reason. There are going to be roads that are closed for days or weeks or months. They'll be power impacts. All those things are going to be a big deal and it's just not where you want to be.

You know, sometimes we have storms that are really hard to forecast. This is a no brainer. It's gonna be bad. A lot of places in the mountains are gonna flood. Some of them will probably be the worst flood they've had. It's gonna be pretty tough.