The force of a Colorado avalanche is hard to comprehend. Thousands of tons worth of snow, ice, rock, and trees, barreling down a slope at speeds up to 200 miles per hour. There is no greater imminent threat to mountaineers in the winter than avalanches in Colorado. However, with the right research, knowledge, skill, and gear, you can reduce the level of risk you face from this hazard. It is impossible to completely reduce the risk of an avalanche – that is important to acknowledge. Never get complacent, and complement this information with a complete avalanche training course to be fully prepared. Here is what you need to know about avalanches in Colorado to stay safe.
An Introduction to Avalanches in Colorado
There are more deadly avalanches in Colorado than in any other state in the United States. Unlike western states which receive large amounts of wet snow, Colorado receives drier air. The snowpack forms more slowly, with longer gaps between snowfall. As the snow sits in the sun, it forms a crust, which forms a weak layer when eventually buried by new snowfall. These layers ultimately fail without warning, while peaks in California and Washington tend to slide during snowfall so that large amounts of snow rarely accumulate. This makes the avalanches in Colorado harder to predict, and therefore more deadly.
The History of Avalanches in Colorado
The first European miners dealt with avalanches in Colorado quite commonly. Given the mines’ proximity to areas at and above treeline, miners were often exposed to avalanches for significant periods of time. In several tragedies, an entire bunkhouse or mine was buried by a slide, with 13 killed in the state’s deadliest avalanche in 1884. It buried an entire small town at the foot of Mount Elbert, the state’s tallest peak.
As the state progressed in the early 20th century, it prevented construction in major slide paths, ending the era of mass burials with numerous victims. With few people exposed to these perils, the death toll dropped dramatically. The number of avalanche deaths reached a low point in the 1940s and 1950s, with only 4-5 people dying annually in the United States.
The explosion of the ski and snowboard industry in the 1960s and 1970s changed this pattern, with numbers rising and peaking in 2011 with 32 annual deaths. Thanks to aggressive education efforts the number had fallen to 20 deaths by 2019, before rebounding slightly in 2021 to 24 following a historic number of deaths that year. With more people heading to the backcountry, many people are concerned that avalanches in Colorado could kill more people in the coming years.
What Causes An Avalanche?
All avalanches in Colorado have three things in common. These include:
- Avalanche Terrain: A steep slope between 30 and 45 degrees.
- Unstable snow: Typically at least six inches of snow is necessary to slide (though not always). There are many causes of snow instability. Wet avalanches occur when melting snow loosens it, while slab avalanches are caused by a collapsing weak layer.
- A trigger: This can be natural or human. 3 out of 4 deadly avalanches are caused by humans, usually the victims.
By understanding these three factors, you can better analyze your situation while out in the field to determine your risk level and manage your position appropriately. Here is a full consideration of each of the three factors, with advice for each you can use while hiking, skiing, or snowboarding in the backcountry.
Watch out for Avalanche Terrain
Avalanches usually occur on a slope that is between 30 and 45 degrees. Anything less isn’t steep enough to begin sliding, and anything steeper cannot gather enough snow to be dangerous. It takes time and practice to learn how to determine a slope’s angle from afar. Buying a slope meter sticker to put on a ski or trekking pole is a helpful way to analyze slopes to avoid slopes prone to sliding. You should not enter avalanche terrain unless you have the appropriate level of training to dig a test pit and identify safe snow conditions.
Be wary of connecting terrain above you. Avalanches often run out onto less steep terrain below the slope it begins on. Give all avalanche terrain a wide berth, and cross below it one at a time just in case it slides. Also be mindful of terrain traps like gullies and couloirs that collect snow. When these slides they can bounce you off and over rocks, increasing your chance of serious injury or death.
Be alert for signs of snow instability
Sometimes it is impossible to know a snow slope is unstable until you are standing on it and it is too late. However, there are a few warning signs you can watch for to identify problem slopes. The most obvious sign are previous or ongoing avalanches on other slopes in the area. If other slopes contain unstable snow, it is likely that the one you aim to climb up does too. If you pass fresh avalanche debris on your hike in, or see avalanches occur in real-time, you may want to consider turning back.
More localized signs of snow instability include shooting cracks that form as you walk near or on a slope. You may also hear a characteristically “wumpf” sounding noise. This is the unstable layers collapsing and sometimes occurs just below a slide. If you see either of these signs, get off the snow slope and out of potential slide paths as quickly and as safely as possible.
Stay away from potential triggers
Avalanches in Colorado start when unstable snow on a steep slope is triggered – force is applied that sends the snow out of balance and into a downhill slide. Most deadly avalanches in Colorado are triggered by humans – not natural sources. Avoiding triggers thus also means not being a trigger yourself. This means avoiding unstable snow, and remembering that you can trigger an avalanche from 1/4 mile away (or more). Avalanches run naturally during and after large storms when wind and new snow triggers slides. It is best to avoid the mountains entirely during these extremely dangerous times.
Cornices deserve special mention as triggers. These large windblown masses of snow form along ridges in winter as snow is blown up and over the mountain. They hang out over the side of a ridge and eventually break away and fall. They can trigger massive avalanches below them without warning. Never stand on top of a cornice, as it may break away. Take special care when hiking up below a cornice, as a fall could spark a large slide. Many of the deadly avalanches in Colorado are triggered by a cornice fall.
Checking the Avalanche Forecast and Condition Report
The phrase “Know before you go” is a critical tip for avoiding avalanches in Colorado. This means researching the avalanche conditions before you visit the mountains so you can plan around the hazards and manage your avalanche risk appropriately.
The best place to go is the Colorado Avalanche Information Center (CAIC). They produce daily avalanche forecasts during the winter and spring for multiple zones throughout Colorado. They issue an overall rating, ranging from 1-Low to 5-Extreme. I recommend staying home anytime the rating is 3 or above unless you have specialized avalanche training. They also include an analysis of the snowpack, with details on the specific types of avalanche to be aware of, what signs to watch for, and specific slopes and terrain to be wary with.
An additional resources for avalanche research is a Backcountry Slope map, like CalTopo below. They allow you to identify avalanche-prone slopes (those between 30 and 45 degrees) so you can ensure your router does not pass through or under large slide paths. Be aware: There may be small, steep slopes that can still slide that don’t show up on these mapping programs, so always be alert out in the field. Trust your eyes more than your map.
Resources for Avalanche Research
Get the Proper Avalanche Rescue Gear
If an avalanche occurs and buries someone, you only have a few minutes to rescue them before they run out of air and begin to suffer brain damage. Statistics show that 93 percent of avalanche victims can be recovered alive if they are dug out within the first 15 minutes, but then the numbers drop catastrophically. After 45 minutes, only 20-30 percent are still alive and after two hours almost no one is alive. You need to move quickly to rescue someone successfully. The right gear is essential for making it happen, including a transceiver, probe, and shovel.
The digital transceiver emits a signal and can also be used to pick up someone else’s signal. This allows anyone buried to be located by others in the group if they each have a transceiver on and correctly set up. Make sure you test your transceiver battery every time you go out and do a check before runs to ensure everyone in your group has theirs on and working. Test out your transceiver and know how to use it before you need to use it.
A transceiver will help you get within a few meters of your buried partner, but that will leave some uncertainty on exactly where to dig. An avalanche probe is a long, thin tube you can quickly assemble and use to poke into the snow, trying to feel for something soft (a person) amid the hard snow and debris. Use your probe in a spiral pattern from your transceiver’s strongest location, and leave it in place once you find someone to mark their location.
Once your probe has found the victim, you will need a shovel to dig them out. An avalanche shovel folds up so you can carry it with you and quickly assemble it when needed. Having multiple shovels on your team is a good idea, so multiple people can dig together and speed up the rescue. Don’t dig down – try digging horizontally into the slope and toward the victim, which allows snow to be moved out more quickly and helps you reach them more quickly following avalanches in Colorado.
What to Do in an Avalanche
If you are hiking or skiing and you see someone in your group hit by a slide, here are some tips for your immediate response. Remember – minutes matter here.
- Watch the victim closely so you can pin point their last known location and start your search from there.
- Do not approach the area until you are reasonably sure it is safe. Small secondary slides are not uncommon, and debris can also be hazardous.
- Do not go for help – it is highly unlikely it will arrive in time. The one exception is if there are other people within sight or noise range – call them over to assist.
- Search for any assign of the victim, including gear, clothing, or small bit of them exposed above the snow. Listen carefully in case you can hear them.
- If you cannot find them visually, get out your transceiver and begin a high-level search using a grid to find the victim’s signal. Then begin a fine search to hone in on their exact location.
- Get your probe out and probe around the strongest signal strength point until you feel something soft.
- Dig into the snow horizontally to extricate the victim.
- Provide emergency first aid if necessary and contact SAR for additional support
Always contact emergency responders following avalanches in Colorado, even if their support is not needed. This ensures it is reported to the proper observers to help inform their reports and forecasts. You will not be punished for triggering an avalanche – always report it.
Avalanche Rescue: It’s All About Practice
It is not enough to buy all the right gear. If you do not know how to use it in the heat of the moment, it might as well be useless. Get out in the snow with a partner and practice rescue in real conditions. Bury a transceiver and practice finding it with your own, probing for it, and then digging it out. All avalanche gear is slightly different, so taking time to get used to it in real conditions is essential preparation.
Many ski areas and mountain towns are putting together practice areas and events specifically focused on avalanches in Colorado. If you live near one I highly recommend visiting and making use of them. They are a fantastic tool for avalanche preparation and training.
Take an Avalanche Education Course. It’s Worth It
At the end of the day, avalanche education courses are the gold standard when dealing with avalanches in Colorado. These programs mix classroom sessions and fieldwork to build your foundational skill and knowledge base around avalanches in Colorado. If you think you will be heading into avalanche terrain repeatedly in the future, I highly recommend taking an AIRE class. While these programs are a bit expensive there are a number of scholarship and financial aid programs you can search for online.
Consider this: Triggering an avalanche puts many people at risk – not just you, but everyone else on the mountain. It strains SAR resources and puts them at risk too. Taking an avalanche education course is a responsible way to protect yourself and others while recreating in the mountains.
Myths about Avalanches in Colorado
Avalanches are popular in pop culture, which has led to a number of persistent myths about them. Here are a few I hear quite often, along with a fact-based response for each about avalanches in Colorado.
MYTH: Avalanches in Colorado usually strike without warning.
TRUTH: Very few avalanches strike completely randomly. 90% of deadly avalanches are caused by the victim themselves. In most situations, signs of instability like shooting cracks and a hollow “whumpf” sound will be present before a large slide occurs. In this sense, avalanches are often predictable to a degree. They rarely strike without warning.
MYTH: Loud noises can trigger avalanches in Colorado.
TRUTH: While you have likely seen this happen in a movie or on television, sound just is not strong enough to trigger an avalanche. People sometimes point to examples of loud storms seemingly triggering avalanches from the noise, this is usually due to high winds and new snow – not the noise. People, wind, new snow, and cornice falls account for 99% of all avalanche triggers.
MYTH: Avalanches in Colorado are usually deadly.
TRUTH: 2 out of 4 people caught in an avalanche walk away unharmed. 1 out of 4 will be seriously injured, and 1 out of 4 will die. Therefore you actually have a 75% chance of surviving an avalanche, and a 50% chance of walking away unharmed. It depends a lot on how big the avalanche is, whether or not victims are buried and alone, and whether there are cliffs, rocks, and large debris that may cause additional injury. However, they usually are not “certain death” as depicted in many movies. Many people have survived many avalanches.
Avalanches in Colorado: Know Before You Go and Stay Safe!
As you can probably see now, there is a lot to know when it comes to avalanches in Colorado. These powerful forces of nature can shatter trees like matchsticks and move boulders as big as cars. Getting a full avalanche training is the best way to protect yourself if you plan to spend a considerable amount of time in the mountains in winter conditions. Here are some of the other top tips we went over in this article.
- Get the gear and know-how to use it: A transceiver, probe, and shovel.
- Always check the forecast and slope map for your route beforehand.
- Practice an avalanche rescue with a simulated victim to search for and rescue.
- Be aware of avalanche terrain, snow instability, and potential triggers.
- Cross slopes one at a time, and always bring a buddy in winter.
Good luck with your mountain adventures this winter; Safe travels on the trail! I hope this helps you better understand avalanches in Colorado.
More Resources About Avalanches in Colorado
Looking for more information about avalanches in Colorado? Here are some websites with good resources and tips. Safe travels on the trail!