It’s been a weird and warm start to winter. But there’s already been a few tragic deaths in the backcountry due to avalanches.
A snowmobiler was buried in the Salt River and Wyoming Ranges recently, and a skier was carried away in the Tetons in December.
To get a sense of it all, Wyoming Public Radio’s Caitlin Tan dialed up Frank Carus, director of the Bridger-Teton Avalanche Center in western Wyoming.
Editor’s Note: More avalanche related information can be found at the sites below:
- Western Wyoming forecasts: Bridger-Teton Avalanche Center
- Eastern Wyoming avalanche observations: Eastern Wyoming Avalanche Information Exchange
- Avalanche forecasts across the U.S.: Avalanche.org
- The avalanche encyclopedia: Avalanche.org
- Avalanche education providers: Briger-Teton Avalanche Center’s recommendations
- Avalanche related grief and trauma resources: Colorado Avalanche Information Center’s recommendations
Editor's Note: This story has been edited for clarity and brevity.
Caitlin Tan: Your job is to go out into the mountains and assess potential hazards in the snowpack. I'm curious. What are you seeing this year that's raising some red flags?
Frank Carus: This year, the pattern is Pacific storms. It started with drought and then weak layers of snow developed. Then we started getting some snowfall, and some Pacific storms brought a whole lot of precipitation and wind – we had a period of three to four feet over about as many days. Some of the crust that developed from those Pacific storms have caused some trouble, some lingering, persistent layers in the snow that have caused some avalanches.
CT: Obviously you're making a lot of your videos and content for an audience of snowmobilers and backcountry skiers, but for listeners who stay inbound, can you explain briefly how avalanches are triggered?
FC: There's really five or six things to look out for, we call them the red flags.
You need to have steep enough terrain for snow to slide.
Anytime you have heavy snowfall – a foot or more in a 24-hour period – [or] if you have rapid warming – and that can be just a much warmer temperature or it can be just a lot of sunshine on a slope after it hasn't had sun, that can trigger avalanches or make them more sensitive to triggering for people.
Rain on snow, that's certainly a red flag.
Wind is also a big deal. Wind picks the snow up off of slopes and moves it on to others, creating a slab of denser snow laying over softer snow, and then persistent weak layers develop due to basically vapor transport through the snowpack, making those grains such that they don't stick to each other, creating a weak layer in the snowpack. Essentially, you can think of that weak layer as corn flakes, and then the slab of snow on top you can think of that as dictionaries. Eventually, those corn flakes just can't hold that weight and fail and an avalanche happens.
CT: Do you know how many avalanches have been recorded in Wyoming so far this season?
FC: We don't track throughout Wyoming.
Editor’s Note: For user submitted reports from eastern Wyoming, check out Eastern Wyoming Avalanche Information Exchange.
But right now, what we're showing is 115 reported avalanches within our forecast zones here in western Wyoming: the Tetons, Snake River, Salt River Range and Togwotee Pass.
That's just reported avalanches. So I would guess anywhere between five and 10 avalanches occur for every one that's reported, at least. A lot of times avalanche cycles occur during those stormy periods when we have limited visibility in the mountains, or just simply limited access due to the danger.
CT: And I'm assuming those range from human caused and natural avalanches?
FC: I would say the majority of those have been natural avalanches. So far, we've had 38 reported human triggered avalanches of those 115.
CT: Are you seeing any specific trends in terms of where these avalanches are happening when we're thinking elevation, aspect, terrain and mountain ranges?
FC: Those patterns change depending on weather and storm conditions. It's really important for people to realize that anywhere a steep slope exists, 30 degrees and greater, you could have an avalanche. The patterns really would be more about those red flags we were just talking about.
Most recently, what we're concerned about in western Wyoming right now, particularly in the southern parts of [our] forecast zones, is a layer that is really spotty. It's in isolated areas, and it's really hard to track. It’s essentially surface hoar that formed around Jan. 1 and 2 on a cold, clear night. The surface hoar, those frost feathers that develop on the snowpack after that snow fell, created a slab on top. Typically, those layers are found in valley locations. They're sheltered from the wind, and so far, very steep slopes are most concerning. But we don't know exactly where that kind of layer exists. I think it's really important for people to realize that it is out there. And in fact, surface hoar can develop in surprising ways, quickly, and can cause problems.
What we're doing now is encouraging people to evaluate slopes. If they can, dig and look for it. That's helpful.
And then the main thing is, don't ski or ride a snowmobile without somebody watching you at all times.
Then, think twice or just avoid steep slopes that end in what we call a terrain trap, which is essentially where a slope meets a flat spot, a stream or a patch of trees. Anything where debris from what might otherwise be a small and relatively harmless avalanche can pile up deeply and make for a prolonged rescue effort if someone does get buried. Remember that people have a limited amount of time to be under the snow before they run out of air. If you get caught in an avalanche, you definitely don't want to be buried very deeply.
CT: So far this season, two people have died in Wyoming due to avalanches. Can you tell us a little bit about what happened, starting with the more recent fatality in the Salt River, Wyoming Ranges? It sounds like that surface hoar layer you were talking about contributed to that.
FC: Yeah, it did. The unfortunate thing there is that the two riders, both really skilled and experienced riders, split up for a moment, with one going onto the steep slope over a terrain trap. The other rider was some distance away, so he didn't realize that his partner had triggered the avalanche until he didn't hear his [partner’s] sled running anymore. At that point, he returned to the scene, thinking that he would find him just stuck in the snow. [Instead] he found that the slope had fractured and his partner was buried. Tragic.
CT: And then it sounds like a skier was caught and buried in an avalanche south of Teton Pass in mid-December. What happened there, Frank?
FC: That avalanche occurred on some wind slab layers following one of the Pacific storms that we were talking about earlier – really high wind speeds and six to eight inches of snow each day for the previous three days.
This pair had gone into some terrain that is very steep, 40 to 45 degrees, even at the start zone. They skied into this gully and triggered an avalanche on one aspect and weren’t comfortable skiing that aspect, so they wrapped around the corner onto another slope. [They] put in what we call a ski cut, meaning they intentionally skied across the start zone in an attempt to see if the snow is stable and trigger an avalanche if it's going to be triggered.
In this case, he put the ski cut in and then continued down and made a couple of turns, and the slab characteristics were such that slope failed well above him, up the slope behind him, so he was not able to escape from the avalanche, and was carried through a narrow gully that has a lot of trees on either side. Those trees created the trauma [that killed him].
CT: How is it for you going day in and day out in this type of job? Sometimes you're playing in the snow, and sometimes it's really, really devastating news, and you're talking to people who've been through something really traumatic.
FC: After having done this for 15 years, those fatalities do take a toll, and the longer I do this, the more I realize that luck is a factor. We approach this objectively and scientifically, but I think that there is some component of luck.
It’s a wicked learning environment. People can go out and play on slopes and not trigger an avalanche, and unknown to them, they were maybe 10 feet away from a thin spot in the slab where we could have triggered something. So we really have to watch for our risk acceptance creeping up when bad things don't happen.
I think personally, my risk tolerance has shrunk. It is a dangerous game. It's super fun to be out in the mountains and in the wintertime, and fresh snow with sunshine is fantastic. It's a great feeling, and you can get all that and keep things on the conservative side and live to go home to your family at the end of the day.
CT: From what I understand, Wyoming averages about two deaths a season to avalanches each year, and we've already hit that. Why do you think this year is starting out so fatal?
FC: Well, anything I could say would be speculation. But I do know that one of the hazards of thinking about getting into the snow is this sense of urgency. There's pent up demand, and people want to get after it, and maybe that affects people's hazard analysis when they do finally get to the trailhead and we do finally get some snowfall.
CT: What would be the bottom line safety message you want skiers, snowmobilers, snowshoers, to really take to heart?
FC: Avalanche forecasts and avalanche education together have contributed to keeping our avalanche fatalities in the U.S., the trend, generally flat and about the same number. That’s despite a lot more backcountry skiers and snowmobilers, a lot more users in the backcountry. So read the forecast, take avalanche courses.
CT: The backcountry community is pretty tight knit, and it feels like accidents can really ripple through. What advice do you have about grief and trauma for folks who've been impacted by avalanche accidents?
FC: Avalanche accidents are pernicious in the way that people are going out for a good time and then tragedy happens. People can't say goodbye. It's just a shocking tragedy that can really impact young people who are in their prime and their families, and just lead to a lot of grief and trauma for the rescuers particularly and those directly involved, like partners.
There are opportunities for help, like the Responder Alliance. People just need to look out for each other and seek help and encourage others too, as well.
