To learn about the Central Oregon Avalanche Center, go here.
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Michael Dunne: I'm Michael Dunne. There's a lot to love about traveling into the Oregon backcountry in winter. It's beautiful. There's hardly anyone around, and it's so peaceful and quiet. But there is an inevitable force of nature that can shatter that peace and quiet in a split second. It's one of the most feared occurrences in the backcountry: an avalanche. Very recently, the most catastrophic in California history claimed the lives of nine experienced backcountry skiers. Today on the show, you'll hear from two experts on avalanches and learn how they form, why they happen, and the steps everyone who ventures into the winter backcountry should take. When it comes to avalanches, the old saying about an ounce of prevention being worth a pound of cure is certainly true. David Hill is a professor at Oregon State University, a member of the Corvallis Mountain Rescue Unit and an avalanche instructor. David, thanks so much for coming on and talking with us.
David Hill: My pleasure. Thank you for having me.
Dunne: Let's start with the basics. What causes an avalanche?
Hill: For an avalanche to occur, there are really three main ingredients. The first is avalanche terrain. This mostly amounts to slopes that are steep enough to have avalanches, usually around 30 to 45 degrees. Flat terrain won't produce avalanches. The second ingredient is some sort of weakness in the snowpack, some instability. Avalanches tend to occur when a lot of recent snow falls onto a weak layer. You can think of this weak layer almost like a layer of ball bearings or marbles, and the overlying snowpack just wants to slide off of it. The third thing you need is a trigger. Something has to actually cause the avalanche to occur. A lot of times that trigger is a person out in the backcountry who steps onto a slope. You can also have natural triggers: hot sun, significant wind, rockfall. So those are the three things. You need the terrain, you need some weakness in the snow, and then you need something that sets it off.
Dunne: As I understand it, there are two basic types of avalanches. Can you describe them?
Hill: We tend to think of avalanches in terms of loose avalanches or slab avalanches. A loose avalanche can occur right after a recent snowfall when there's light, fluffy, powdery snow that comes loose and slides down the hill. That's a dry loose avalanche. Here in the Pacific Northwest, we also get a lot of what are called wet loose avalanches, typically in May and June, when strong sun and warm temperatures melt the surface layers of the snowpack. That wet slide moves slowly down the hillside. The other type is a slab avalanche, which is what most people are classically familiar with: a big torrent racing down the side of a mountain. A slab avalanche occurs when a cohesive layer of snow, almost like heavy blocks of Styrofoam, breaks loose and tumbles down the mountain. Both types are dangerous, but slab avalanches tend to lead to more significant injuries or fatalities.
Dunne: In the Cascades, are there areas that are avalanche-prone, where we see avalanches occur again and again year over year?
Hill: That's a good question, and somewhat surprisingly, I would say no. If you look at the fatalities we've had in Oregon over the past five years, about seven in total, they're pretty spread throughout the state. There's one out in the Wallowas, one down on Mount Bailey, some up in the Broken Top area, one up on Mount Hood. They really cover all corners of the state, which is not a very comforting thing to hear. A couple of other things to note: Oregon tends to have fewer avalanche fatalities compared to some other states. Part of that has to do with terrain. Our mountains are volcanoes, so their angles are a bit more gradual than some of the really craggy Rocky Mountain states. Our weather also plays a role. We tend to run a little warmer in the Pacific Northwest, so our snowpack is a little heavier and in some cases bonds well and becomes stronger than in some Rocky Mountain states, where snowpacks may be more unstable.
Dunne: I've heard that ski resorts work to make sure their slopes are safe. What are some of the ways they do that? Do they essentially act as a human trigger using certain devices?
Hill: There's a lot of variety depending on the particular resort, but all resorts will have a snow safety team that's out daily assessing the snowpack and doing mitigation. That mitigation can take many forms. In some cases, ski patrollers go up to areas where a cornice is hanging over a slope and stomp on it to get it to release and create an avalanche below. In some areas, they use explosives, either hand-thrown charges or charges dropped from a tower. Back in the day, some areas would use artillery to lob charges at certain slopes. There's a variety of ways that ski patrol can safely initiate an avalanche to reduce the loading on the snowpack when guests are not in the area.
Dunne: We've talked about skiing. Are there other outdoor activities that are prone to triggering avalanches?
Hill: When you look at the history of serious avalanche accidents or fatalities in the United States, it has traditionally been backcountry tour skiers. Snowboarding and splitboarding have become quite popular, so those are other user groups out there. I would say the one thing that has really crept up on the radar in the past 10 to 20 years is people on snowmobiles. Those machines have become lighter over the years and allow people to get deeper into the backcountry. People on motorized devices, outside of wilderness areas, are increasingly subject to avalanche hazards. One great development is that the snowmobile community has really stepped up its promotion of avalanche education.
Dunne: I want to get to education and safety precautions. What are some strategies, and what advanced equipment is available to the public to make a backcountry adventure safer?
Hill: The main thing with backcountry travel is that you are farther away from care than you would be at a ski resort, and that's really what I think about most. Things can go wrong, and it's going to take longer to address them. I think about safety gear in three categories. First, there's personal gear: extra clothing, food, water and perhaps a medical kit in your backpack. Second, there's avalanche rescue gear, which largely consists of a beacon, a transceiver that everybody wears, a shovel and an avalanche probe. An avalanche probe is essentially a segmented aluminum tent pole. Third, there's emergency gear. When traveling in a group in the backcountry, you want an emergency beacon like a Garmin inReach, because you may not have cell service. You might also carry extra clothing, a foam pad or an emergency shelter, all the things that allow you to take care of yourself and your teammates and stay warm and dry if there's an accident and you're out in the wilderness for a while.
Dunne: I almost apologize for getting morbid, but if you're caught in an avalanche, what do the statistics say about survivability? What's the probability of survival if you're with people who see what happened? And can a buried person excavate themselves?
Hill: Excavating yourself is highly unlikely. One thing many people aren't aware of is that when a slab avalanche comes to rest and sets up, that material is extremely heavy and dense. It's not the light, powdery snow people imagine, so self-rescue is rarely possible. In terms of survivability: studies of avalanche victims show that when there is a fatality, about 75% of the time it's due to asphyxiation, and about 25% of the time it's due to trauma from colliding with a tree or a rock. Survivability drops pretty quickly after about 30 minutes of burial. That means if someone is caught in an avalanche, you have roughly 10 to 20 minutes to act quickly, locate them, dig them out and provide medical care.
Dunne: My last question: We exist in an era of climate change. Does climate change make avalanches more or less prevalent?
Hill: That's a good question. I think it's important to realize that an individual avalanche is not so much a climate phenomenon as it is a weather phenomenon. It's the response of a landscape to what has been happening over the past week or two in terms of weather: temperatures, snowfall and so on. Climate and climate change involve much longer periods and trends. In the avalanche space, what is on people's minds is that with warming temperatures, particularly here in the Pacific Northwest, snowfalls are heavier and wetter, and therefore have more mass. So if there are avalanches, there is a bit more mass being carried down the hillside, with the potential to do more damage to people and infrastructure.
Dunne: Professor David Hill from Oregon State University, also a member of the Corvallis Mountain Rescue Unit and an avalanche educator. Professor, thank you so much. This has been great.
Hill: Of course. My pleasure.
Dunne: Now let's hear from an expert who helps forecast avalanches. Gabriel Coler is the lead forecaster for the Central Oregon Avalanche Center. Gabriel, thanks so much for coming on.
Gabriel Coler: Awesome. Thank you.
Dunne: Give us an overview of how your organization works.
Coler: The Central Oregon Avalanche Center's main mission is to give people information about avalanche danger and about the snowpack in Central Oregon. Our forecast zone runs from basically Mount Bachelor in the south up just north of Santiam Pass and Three Finger Jack. Each day we put out a forecast for the following day, rating how dangerous avalanche conditions will be.
Dunne: Take us through what you do when you go out in the field. How do you determine what's at risk, what might slide?
Coler: It's complicated, but basically when a forecaster is out in the field, they're targeting weak snow. Weak snow is what leads to avalanches. They're looking for weak snow, and particularly weak snow buried underneath harder layers, because that's when we tend to get more destructive slab avalanches. Forecasters are digging holes in the snow, looking at different slopes and looking for avalanches that may have occurred naturally. When they come in from the field, we also gather information from partners such as local ski areas and guide services to see what they're observing in the snow. Then we do a deep dive into the weather forecast to see how conditions will change overnight, and that allows us to predict the avalanche danger for the following day.
Dunne: Can you look at a slope and be suspicious? Does the work you do become intuitive, or are you mainly relying on digging into the snowpack to see what it's made of?
Coler: Both, really. I always say that to be a good avalanche forecaster, even if you only work one day a week, you're essentially doing your job every day of the week. You have to constantly know what's going on in the snowpack so you can see changes over time. That gives you a certain intuition, because you've looked at the data: how much new snow have we gotten, is it falling on weak snow, and so on. Once you've digested the data, you can develop your intuition from there. You do get to the point where you can intuitively think, let's avoid that slope, but only because you have that history with the snowpack. If you dropped me somewhere with no previous information, I really wouldn't know what was going on. I will say that something we're always trying to educate people on is that avalanches occur on slopes between 30 and 45 degrees of steepness. I'm always telling people: you can go out in the backcountry and as long as you avoid those steep slopes, or being underneath them, you don't really have to worry about avalanches, no matter how dangerous the conditions are.
Dunne: So some slopes are too gentle for the energy to build up, and some are so steep that snow can't really get a foothold. Is that roughly it?
Coler: That's pretty close. Picture a flat meadow at one extreme: you can't have an avalanche there because there's no gravity pulling at the snow. That holds up into the mid-20-degree range, almost all the way to 30 degrees. And then on really steep slopes, picture the extreme of a vertical cliff: the snow is just constantly sloughing off.
Dunne: This may be hard to put into words, but can you contextualize what a 30-to-45-degree slope actually looks like? For example, is a black diamond or double black diamond ski run in that range?
Coler: All ski areas are a little different, but in general your black diamond and double black diamond slopes are the ones that are going to be in those angles. Some blue square slopes exceed 30 degrees depending on the ski area.
Dunne: In Hollywood movies, we sometimes see a skier racing an avalanche. Is that even really possible? I imagine avalanches can move a lot faster than most people realize.
Coler: Avalanches can move very quickly. With slab avalanches in particular, a skier or rider might trigger the avalanche, but that avalanche is going to propagate all around them very rapidly, which makes it extremely difficult to outrun.
Dunne: When you gather the data and put it together, how does your website work? How can people access your forecasts before heading into the backcountry?
Coler: If they're heading out in Central Oregon, they can go to coavalanche.org. The first thing they'll see is what we call the bottom line, where we write two or three sentences with no jargon explaining the situation. For example, last night I wrote that avalanches are likely and could be large where wind has blown in new snow. We try to make it as simple as possible to tell people where the hazard is greatest and how dangerous it is. We also give it a danger rating using the North American Public Avalanche Danger Scale, which goes from low all the way up to extreme: low, moderate, considerable, high and extreme. A lot of people probably just see the color, like yellow for moderate, and ballpark it from there. But if they were to dig in deeper, there is very specific travel advice for each danger level.
Dunne: Gabriel Coler, lead forecaster for the Central Oregon Avalanche Center. Gabriel, really appreciate you coming on.
Coler: Thanks, Michael.
Dunne: That's the show for today. All episodes of Oregon on the Record are available as a podcast at KLCC.org. Tomorrow on the show, it's one of the biggest local stories in our community: the challenges facing PeaceHealth, and we'll talk to their chief hospital executive. I'm Michael Dunne, host of Oregon on the Record. Thanks for listening.
