Avalanche! Plus Extra Interview with Avalanche Expert Art Judson
04/01/2012 01:00 ● Published by Kelly Bastone
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Nick Herbert triggers a small slide on Little Agnes. Photo by Aryeh Copa.
The Slippery Slope Argument:
by Kelly Bastone
Locals think Steamboat and its surrounding peaks are safer than other, more avalanche-prone parts of Colorado. Are they right?
In the gray light of his bedroom, a low, powerful rumble wakes Dean Pulford. An avid resort and backcountry skier who typically notches 100-plus days a year, Pulford checks the snow report as soon as his eyes open each morning. But from the growl he heard this morning, he already knows it’s going to be a powder day.
In Steamboat Springs, snowplows wake powderhounds with a roar that crescendos and fades like the sound of ocean waves. But at other resorts – such as Alta, Utah – artillery shells and bombs, not plows, signal riders to ready their powder boards. There, dozens of named runs follow known avalanche paths, and mitigating the slide risk often takes patrollers most of a morning. Every year, about 22,400 pounds of explosive hand charges are used to control slides in Big and Little Cottonwood Canyons, home to Alta, Snowbird and Brighton.
And at Steamboat?
“It’s more like 800 pounds a year,” says Kyle Lawton, the avalanche and snow safety team leader for the Steamboat Ski Corp. “Our avalanche concern is much less than at some other areas.” His 10-person team usually readies Steamboat’s slide-prone zones before the lifts open, even after the biggest storms. Their control work is meticulous and effective, but it can’t guarantee stability on every square foot of the 2,965-acre resort. Beyond the resort’s boundaries, in Fish Creek Canyon, on Buffalo Pass, and at other powdery Park Range slopes that attract skiers and snowmobilers, avalanches regularly occur – and they’re more powerful than most people realize.
Despite the constant reminder that our mountain is named for Buddy Werner, a local Olympian who died in a 1964 avalanche in Switzerland, “people here tend to be overconfident,” says Eric Deering, an avalanche instructor and operations manager for Steamboat Powdercats. Powdercats operates snowcat tours on 6,000 skiable acres atop Buffalo Pass.
Terrain around Steamboat typically looks different from the jagged peaks and huge bowls common across other Colorado mountain ranges. Berthoud Pass, for example, is creased with deep gullies plowed by repeated avalanches, and those huge, above-treeline bowls and obvious slide paths fill onlookers with respect and awe: It’s easy to imagine the crushing power of snow as it plunges down a 2,000-foot chute.
Skiers do encounter those clear, long slide paths in the Zirkels, Elkhead Mountains and Flat Tops, where steep, treeless faces create avalanche threats on par with the rest of the state. But on Mount Werner and the summits closer to town, the avalanche paths aren’t as obvious, says Deering, a certified American Institute for Avalanche Research and Education instructor: “They’re shorter, and less defined, so people don’t give them the credit they’re due. They think, ‘I can ride it out.’”
The region’s 10 avalanche fatalities – including one within the ski area boundary – suggest otherwise. “They weren’t what you’d call big slides,” Deering says. But avalanches are like lightning bolts: Even little ones can be lethal. Compared to the Alps, which have buried entire villages beneath a tsunami of snow, Steamboat area slides may seem small. Humans, as it turns out, are smaller still.
A backcountry skier exits the Steamboat Ski Area through a well-marked gate. Photo by Aryeh Copa.
Anatomy of an avalanche
Steamboat Springs, CO - Colorado is notorious for avalanches. The relatively shallow snowpack, along with cold temperatures and high winds above tree line, creates “the worst combo you can get for snow stability,” Deering says.
In the high elevations, snow starts falling as early as September, but it doesn’t pile up – at least, not until later in the season. As the snow loses heat, the flakes are transformed from spiky crystals (which bond as a stable blanket) into poorly bonded facets. Faceted snow is characterized by angular crystals that can be small, but can grow larger with steps and striations on their surfaces, often called depth hoar. When mid-winter storms pile heavy snows onto this sugary layer, the weakly bonded grains fail -- and avalanche.
Steamboat’s scene works a little differently. Because Mount Werner and neighboring summits are lower in elevation, they generally get snow later – and it piles up faster than higher elevations in our zone. With an average annual snowfall of 347 inches, Steamboat receives more snow than most Colorado resorts. The Tower measuring site at 10,500 feet, on the summit of Buffalo Pass averages more than 600 inches per year, making it the snowiest location in Colorado. That thick snowpack insulates the cold air from the warm ground and helps prevent weak, faceted snow layers from forming.
Also, because it sits below tree line, Steamboat typically receives less wind – a key avalanche-producing factor. Fast-falling snow accumulates at one to two inches per hour, but wind-blown snow can pile up 18 inches (or more) per hour, placing a sudden, massive stress on a snowpack that may not be strong enough to support the load. “It’s all about stress and strength,” Deering says.
When stress exceeds the snowpack’s strength – as can happen when a skier or snowmobiler plunges into the snow– the blanket rips away from the slope and surges downhill. That happened on the ski area in 1972, when an avalanche on Steamboat’s Crowtrack run swept away five skiers, fatally burying one. It was more than 30 years before the ski area saw another in-bounds slide. In January 2005, a snowboarder ducked the closure ropes and triggered an avalanche to riders’ left of Chute 3. No one was injured, but the fracture line at the top was reportedly almost three feet deep, carrying all the snow off the rocky exposure 50 to 75 yards to the bottom.
But most accidents happen in the backcountry: In recent years, skiers and snowmobilers have died on Soda Mountain and Chedsey Creek (near Buffalo Pass), on Farwell Mountain (near Hahn’s Peak Village) , Grizzly Park (near Walden), and in the Flat Tops. One fatality occurred at a home on Spruce Street, when the entire winter’s snow cover slid off a roof and buried the man who lived there.
“It doesn’t take a big avalanche to kill you,” says Art Judson, a retired avalanche forecaster who founded Colorado’s warning system back in 1962. A ten-foot snow stake protrudes from the yard of Judson’s Steamboat Springs home and his computer’s screen saver displays a photo of Hahn’s Peak and its most prominent slide paths – including the Milly O, a shiver-inducing chute that he named after his wife. “That’s a beautiful avalanche path,” he says, admiring his dangerous specimens the way an entomologist delights in a scorpion. Judson has studied snowy mountain slopes for 60 years, working as a U.S. Forest Service snow ranger at Berthoud Pass and Arapahoe Basin, then doing research at the Forest Service’s Range and Experiment Station in Fort Collins before moving to Steamboat, where he still contributes weather, snow and avalanche observations to the Colorado Avalanche Information Center.
Judson loves avalanches, but he hardly romanticizes them. “The forces are much greater than people think,” he says. “One to ten tons per square meter is typical for a medium-sized slide.” That makes getting hit by a bus seem like a gentle nudge. And avalanche rubble is so heavy (think blasted cement, not fluffy powder) that 12 inches is all it takes to paralyze and suffocate a human body.
Keeping it safe and sane
To mitigate avalanche risk on its four slide zones, the Steamboat Ski Area employs Lawton, who begins studying the snow as soon as it starts falling each season; then he keeps a close eye on subsequent weather patterns that influence the snow.
Skier traffic lowers the slide threat somewhat, since riders churn up weak layers and pack down the snow, resulting in more stability than is typical on low-traffic backcountry slopes. But when a big storm dumps a particularly heavy load on that compacted surface, Lawton and his team reach for explosives: By dangling two-pound charges just above the snow or by tossing them directly onto the slope, Lawton checks the snow’s weaknesses before the day’s skiers and snowboarders do. The practice doesn’t eliminate all risk (charges were detonated the day the skier died on Crowtrack) but it comes close.
Lawton also created Beacon Basin, a practice area located at the top of the Sundown lift. Four avalanche transceivers buried there give resort patrollers and guests the opportunity to hone their search skills: By switching their avalanche beacon from “send” to “receive,” searchers can track the signals to their sources – just as they would if a member of their group were buried in an avalanche.
Deering emphasizes that education can help keep people safe in the backcountry, and avalanche courses teach participants how to recognize risk factors and choose safer routes. “Out there with Powdercats, we see some crazy stuff,” says Deering, who routinely encounters people skiing alone (with no one around to notice or dig them out should they become buried) or groups skiing without avalanche safety equipment (such as a beacon, shovel and probe). Overall, he says, Buffalo Pass skiers, snowboarders and snowmobilers tend to discount the danger – even after they’ve been caught in a slide. Case in point: When a cat operator encountered a man struggling to pull himself out of some debris, the skier insisted, “It wasn’t an avalanche, I just got covered up with some snow.”
Education is worthwhile, says Judson, a former avalanche scientist and national avalanche lead instructor. But after 60 years of snow study and forecasting, he feels sure of just one thing: It’s impossible to predict the behavior of any snow slope. “You can estimate trends and make predictions for groups of slide paths in certain zones,” he says. “But you’ll never know for sure whether a slope is safe or not.”
That’s Pulford’s motto too. Although he regularly skis beyond Steamboat’s boundary gates and reaches backcountry pitches via snowmobile, he’s conservative about assessing slope stability. “There’s nothing like Steamboat powder,” he says. “But no run is good enough to be the last hurrah.”
Know Before You Go
By Jennie Lay
Two pros weigh in on avalanche safety“It is very foolish to think that the snow in Steamboat is safer than other places. The laws that govern snow here are the same as Alta. The physics are the same.” – Art Judson, veteran avalanche scientist and founder of Colorado’s Avalanche Warning Program “We are all apprentices in a craft that has no masters. It’s still a young science, evolving almost daily.” – Eric Deering, certified American Institute for Avalanche Research and Education instructor.
How long have scientists been studying avalanches?
Nearly a century, says Judson. The Swiss have had teams of avalanche researchers studying all facets of the phenomenon in and above Davos since about 1930. The U.S. Forest Service started avalanche studies at Alta, Utah, in the 1940s, then at Berthoud Pass in 1950. Artillery control of avalanches was perfected at Alta by 1957. In 1961 the Forest Service’s research branch began year-round work at the Rocky Mountain Station in Fort Collins. This continued until 1985, when the project shut down due to lack of federal support. The Berthoud Pass studies ceased in the early 1960s, although the research group in Fort Collins had a field station there until 1984. Snostudies at Alta were discontinued in the mid 1970s.
Has snow science changed – Do we know more today than we used to?
“No and no,” says Judson. “We know less today about avalanches than in the 1980s because of the loss of the avalanche scientists who worked at Alta, Berthoud Pass and Fort Collins. The primary loss occurred in blowing snow research and avalanche modeling, none of which continued after 1985. Work in the avalanche warning and forecasting centers in Colorado, Utah and elsewhere in the U.S. survived the closure of the research centers…although financing for the centers outside Colorado is thin.”It’s all relative, says Deering: “In Colorado, our awareness came from miners working up high and getting killed by avalanches. It seemed like a fluke. They thought sound waves triggered them when the railroad or ore cart went by, which led to the myth of ‘don’t yell in the backcountry.’ Now there are full degree programs in snow science and hydrology.”
What does Steamboat’s snowpack look like this year?
Speaking in the midst of an ongoing dry-spell in mid-January, Deering warns, “The snow that we do have on the ground is so rotten. The few strong layers we have were created by wind and sun. Real appreciable snow means we need to be really alert. It’s a horribly weak snowpack down low and the layers aren’t going to fix themselves and go away. You can expect avalanche danger to rise appreciably as soon as we see new snow load.”
In addition to unstable layers, what are some factors that raise avalanche risk?
Snow load: As a heavy layer of new snow piles up on a deep layer of depth hoar (sugar snow), danger rapidly increases. “Any time a new load is added to the snowpack, whether it’s precipitation or wind-transported snow, backcountry users should look at it as a potential red flag,” Deering says. Rain: Heavy rain on cold powder snow can cause loose wet slides and wet slab avalanches which may go clear to the ground and run long distances on low slope gradients. Temperature: Warm temperatures break down the bonds between grains. The first deep warm-up of winter tends to form deep slabs. These are difficult to forecast and very dangerous.
How do you determine the likelihood of an avalanche?
Any snow cover that emits a “whumph” is dangerous and prone to avalanche. “In the final analysis, it is almost impossible to determine how soon a steep slope will react to the weight of human beings on foot, skis, snowboards or snowmobiles,” Judson says. If fresh avalanches are present in the vicinity of a slope you plan to descend, assume it’s unstable and avoid it.“Digging a pit and trying to identify different snow grains only gives you so much information. We get the most information by watching the history of the weather. Knowing how the snow came down, and how it has changed on the ground, gives us great clues about the snowpack and its relative stability,” Deering says.
What are the must-haves for backcountry travel pack?
“A beacon, probe and shovel. Without one, the others aren’t as effective. Digging with a ski is near impossible in avalanche debris,” Deering says. It wouldn’t hurt to have a slope meter either, since avalanches tend to occur within a distinct slope angle range of 30 to 45 degrees. “37 to 38 degrees is the magic number where most avalanches are triggered. A meter will help train your eyeballs, especially around here where we have many more subtle, undefined avalanche paths.”
What precautions should backcountry travelers take?
“Traveling in avalanche areas is risky business at best….People should not go anywhere with a beacon that they would not go without one because over 60% of those buried with properly working beacons are recovered dead,” Judson says. Key safety precautions: Cross avalanche slopes one at a time. Ski from safe point to safe point (i.e., don’t stop at the bottom of the slope, but in trees off to the side). Keep constant visual and auditory contact so everyone knows if something does move. Be aware of terrain traps like rocks, outcrops, boulder fields, or creek beds and depressions.
Where can you get avalanche training in Steamboat?
Take a course, then practice. “Time out in the snow is critical. You have to be out there in it and interact with the weather and the slope. Get the education, then get out and use it,” Deering says. Steamboat Powdercats offers American Institute for Avalanche Research and Education Level I avalanche courses each January. There may be an additional one in March this year. This is a 24-hour introductory course on Buffalo Pass for those planning on traveling and recreating in avalanche terrain, focusing on the basic skills necessary to manage your risk.
www.steamboatpowdercats.com/avalanche-training-courses/Ski Haus hosts an avalanche information clinic in partnership with the Colorado Avalanche Information Center in January each year, with a field session on Rabbit Ears Pass. www.skihaussteamboat.com —
More from the expert: Art Judson's un-condensed responses to our avalanche safety inquiries
Steamboat Magazine: On some days, the avalanche risk is higher than others. What factors contribute to the higher risks?
Art Judson: Some weather and snow conditions which raise risk and cause avalanches:
1. A heavy layer of storm snow lies on a deep depth hoar (sugar snow) underlayer. Danger rapidly increases with an increase in storm layer depth. One of the most common causes of widespread avalanche cycles (slabs) during and immediately following snowfall. Avalanches may run in the depth hoar layer or go to ground. Easy to evaluate and forecast.
2. A wind event follows a snowfall or series of snowfalls without wind. Has resulted in dangerous slab avalanches in less than 12 hours. Easy to evaluate if closely monitored with instruments and observations. Otherwise it catches people off guard.
3. Windpacked new snow is separated from a hard underlayer by a thin layer of surface hoar. Favorable for slab avalanche formation, but occurrences can be spotty because surface hoar is not very durable and can be destroyed by sun or wind.
4. Any snow cover that emits settlement noises (whumphs) should be considered dangerous and prone to slab avalanches.
5. Aged snow layers separated by depth hoar are covered by deep new snow. Slab avalanche danger.
6. Heavy rain on cold powder snow. Loose wet slides and wet slab avalanches which may go clear to the ground and run long distances on low slope gradients.
7. Graupel layers buried by deep fresh wind deposits. Danger of soft or hard slab avalanches.
8. Deep new snow layer over a smooth crust. Crusts formed by rain are more efficient avalanche producers than are sun crusts in such circumstances.
9. The first full depth warm up of winter tends to form deep slabs. Difficult to forecast and very dangerous.
Steamboat Magazine: People have been studying avalanches for hundreds of years. How has the science changed recently? Do we know more today than we did in previous generations?
Art Judson: No and no. People have been studying avalanches for about 100 years and the Swiss have as much experience as anyone because they have had teams of avalanche researchers studying all facets of the phenomenon since about 1930. Their primary research and field labs have been located in and above Davos. Avalanche research in the U.S. began with Forest Service snow and avalanche studies at Alta, Utah in the 1940s and Berthoud Pass, CO in 1950. This work was conducted by the National Forest System. Artillery control of avalanches was perfected at Alta by 1957. In 1961 the research branch of the Forest Service began avalanche research year around at the Rocky Mountain Station in Fort Collins, CO. This work continued until 1985 when the project was shut down due to lack of support at the Washington D.C. office of the agency. The snow studies at Alta were discontinued in the mid 1970s while the Berthoud Pass studies ceased in the early 1960s. The research group in Fort Collins had a field station at Berthoud Pass from 1962 until 1984. We know less today about avalanches than in the 1980s because of the loss of the avalanche scientists who worked at Alta, Berthoud Pass, and Fort Collins. The primary loss occurred in blowing snow research and avalanche modeling, none of which continued after 1985. Work in the avalanche warning and forecasting centers in Colorado and Utah and elsewhere in the U.S. survived the closure of the research centers and has spread to all the western States and New Hampshire although financing for the centers outside Colorado is thin.
Steamboat Magazine: Hodoes one go about determining the likelihood of an avalanche?
Art Judson: Whole books, PhD theses, numerous scientific papers, physical and statistical avalanche models, and various avalanche schools varying from a few hours to a week in length are dedicated to this complex subject. It is difficult if not impossible to explain the process in a short paragraph or two owing to intractable complexities on avalanche paths in the real world. All that will be attempted here is to broad brush the subject in the simplest of terms. For obvious reasons the treatment will be incomplete and will be limited to slab avalanches. Adding difficulty to the process is the fact that the properties of snow are highly variable in time and space and are subject to continuous change. The likelihood of an avalanche on a given slope is determined using a mix of atmospheric science, snow physics, physical tests, and empirical experience. Basic knowledge to begin the determination includes good avalanche occurrence data from the surrounding area, a history of the snow layers in the snowpack, information on the degree of bonding between snow grains, number and placement of weak layers, strength of the layers, and recent weather including recent snow deposition. An understanding of the radiation balance of the snow cover is needed and a high level of skill is essential. One of the quickest ways to determine snow stability is to watch the reaction of snow to the application of explosive charges. We can observe how snow responds to test skiing. If there are collapse noises or shooting cracks, or an avalanche, the snow is unstable. If none of these signs is evident the snow may still be unstable or stable. The more stable it is the larger the trigger needed to make it fail. If fresh avalanches are present in the vicinity of the slope in question one can assume instability and it is prudent to avoid all steep slopes (usually any gradient over 30 degrees is considered steep and will produce an avalanche). Gradients for roof avalanches are much lower although these are no less deadly. Inductive logic of the scientific method dominates the process. In the final analysis it is almost impossible to determine how snow on a steep slope will react to the weight of human beings on foot, skis, snowboards, or snowmobiles. The best we can do is determine general likelihood of failure and use explosive control where people must go into avalanche areas. Andre Roch, one of the most famous Swiss avalanche scientists and a very experienced mountain guide said what he had learned after decades of avalanche research was to never ski avalanche paths (although he had skied hundreds of them). He lived to the ripe age of 98 or 99.
Steamboat Magazine: What precautions should skiers/riders take in avalanche-prone areas?
Art Judson: They should realize that traveling in avalanche areas is risky business at best and if they keep doing it sooner or later they are going to be involved in an avalanche, hurt, or killed. People should not go anywhere with a beacon that they would not go without one because over 60% of those buried with properly working beacons are recovered dead. Crossing avalanche slopes one at a time while others observe from a safe location is advisable as is carrying shovels and probes. The family that tours in an avalanche area close together get buried close together. One of the rules of thumb is that a weekend ski disaster starts with someone's intuition than an avalanche slope is safe to ski or ride.
Steamboat Magazine: What makes an avalanche expert? Who employs them?
Art Judson: A solid science background, many years of on the job training and daily field work consisting of avalanche control, forecasting, and hazard evaluation coupled with years of research makes a good avalanche expert. They have been employed by the U.S. Forest Service and other government agencies. Power and mining companies, state highway departments, cities, railroads, trans-mountain water diversion projects, pipeline contractors, private enterprise, and some developers need their expertise. Many are private consultants.