High hopes for the new year

Everyone hoped 2021 would be a significant change from 2020. We’d see a major weather pattern change. It would finally snow. We’d put the weak, shallow snowpack behind us. Life would be good. We’d have a stable snowpack with more powder than we could ever track up. Unfortunately, no such luck. We’d start and finish January well below the 1981-2010, 30-year median snow water equivalent (SWE). The snowpack would continue to break down and weaken. We’d see over a week of clear sunny weather in the middle of the month, which was nice at the time, but would form a weak layer in the surface snow, which was not so nice after it started to snow later in the month.

A few small storms brushed through Colorado the first week of January. Although we saw a dramatic decrease in avalanche activity compared to the end of December, reports of avalanches kept flowing into the CAIC at the beginning of the New Year.

Around 8 inches of snow fell in the Northern Mountains during the first 8 days of January. In many areas, this new snow made up the entire slab for the season resting on a weak completely faceted snowpack. The new snow combined with strong winds touched off a widespread avalanche cycle in the Northern Mountains. Ninety avalanches were reported to the CAIC in the first 8 days of January in the Northern Mountains alone. Nineteen of those occurred naturally, and 32 were human triggered. Over 50 avalanches were large enough to bury, injure, or kill a person (Size D2 or larger). Backcountry travelers triggered many of these avalanches remotely from a substantial distance.

January 8 was a spectacular day for large avalanches. In one day, a group of riders remotely triggered a very large avalanche on Grouse Mountain outside of the Beaver Creek Ski Area boundary, which was caught on video. Then in two separate events, which were also both caught on video, a snowboarder was caught in a large avalanche on Loveland Pass where he deployed his avalanche airbag and ended up on the surface, and a snowmobiler near Jones Pass was enveloped in the powder cloud from a very large avalanche which he triggered frow lower in the path. He narrowly outran the slide. Both riders escaped unharmed, but they were both very close calls and could have easily resulted in burial, injury, or death.

The CAIC issued a Special Avalanche Advisory on the evening of January 8 for the Front Range and Vail and Summit County zones for the upcoming weekend. The statement warned backcountry travelers to avoid steep north, northeast, east, and southeast-facing slopes in those two zones since that is where people were triggered the bulk of the large avalanches. Nobody reported being caught in an avalanche over that weekend.

The Central Mountains picked up about 6 inches of snow from the early January storms. Fifty-four avalanches were reported to the CAIC in the Central Mountains in the first 8 days of January. Twenty-four of those were size D2 or larger. Many were remotely triggered.

The Southern Mountains fared the best for snowfall at the beginning of January, with two storms totaling a foot of snow in favored areas in the North San Juan Mountains zone. Observers reported 60 avalanches to the CAIC. Twenty-seven were D2 or larger.

And then, it wouldn’t snow again for what felt like an eternity.

It was Groundhog Day for the next ten days. Every day was clear skies, warm days, cold nights, large temperature swings between night and day, light northwesterly winds, and no precipitation.

During prolonged periods of high pressure like this, the surface snow goes through a process called near-surface faceting where large diurnal temperature swings cause the top foot (30 cm) or so to facet and weaken. This isn’t a problem when this weak layer is at the surface, but as the title of the article by Karl Birkeland in the Autumn 1998 issue of The Avalanche Review suggests, “Sometimes Today’s Great Skiing Creates Tomorrow’s Avalanche Headaches.” Nothing would prove closer to the truth at the end of January.

During the period of high pressure from January 9 to January 17, observers reported 66 avalanches. About half of those avalanches were large enough to bury or injure a person. Most broke in the weak snow near the ground. Many were unintentionally or remotely triggered.

The high-pressure ridge to our west began to break down on January 17 which opened the door for a storm to move into the Northern Mountains overnight into January 18. The Northern Mountains received 6 to 8 inches of snow in the Flat Tops, the Park Range, and the northern Front Range. This wasn’t quite enough snow to build thick slabs, but it did cap the weak near-surface faceted crystals that formed during the previous 10 days. Observers only reported a handful of avalanches from this storm in the Northern Mountains.

Snowfall tapered quickly with only a couple inches of snow in the Central Mountains, and even less in the Southern Mountains, but that was about to change.

Back to back low-pressure systems moved into the Great Basin beginning on January 21 bringing good moisture on a strong southwesterly flow. This would be the first real test of the newly formed weak layer and in areas in the Central and Southern Mountains that got the brunt of the storms, it wouldn’t hold up well.
The focus of the next series of storm stayed south, and the Northern Mountains pretty much missed out on the action with accumulations of only about 3 to 6 inches across the area. We didn’t see many avalanches during or right after this storm in the Northern Mountains.

Six to 18 inches of new snow fell in favored areas of the Central Mountains on January 23 setting off a pretty good avalanche cycle especially north and west of the town of Crested Butte. Avalanches were breaking easily on the near-surface faceted crystals buried at the new/old snow interface and easily stepping down to the ground. Observers recorded 58 avalanches in the Central Mountains from January 23 to 26. Thirty-nine of those were in the Gunnison zone.

The Southern Mountains always do well on a southwesterly flow especially areas in the South San Juan Mountains zone. Areas favored by the southwest flow picked up 8 to 12 inches of new snow with around an inch of snow water equivalent (SWE) on January 20 and then another 5 to 8 inches on January 23. By January 27, storm totals at Telluride were 27 inches with 2 inches of SWE, on Coal Bank Pass storm totals were 38 inches of snow with 2.95 SWE, on Wolf Creek Pass storm totals were 40 inches of snow with 4.3 inches of SWE, and in the La Plata Mountains storm totals were 46 inches of snow with almost 2.5 inches of SWE. Observers recorded 100 avalanches in this time period. About half of those were large enough to bury, injure, or kill a person. Two backcountry skiers were caught in avalanches in the North San Juan Mountains zone on January 24, one near the town of Ophir and another near Red Mountain Pass. Both escaped unharmed.

The final storm in January arrived just before the end of the month on January 30 and lasted through January 31.

Light snowfall started on January 30 in the Northern Mountains, but the snow really didn’t start to accumulate until the winds shifted to the northwest on January 31. Two day snow totals were about a foot in the Steamboat and Flat Tops zone, 8 inches in the Front Range zone, and 12 inches from Vail to Breckenridge in the Vail and Summit County zone. Between January 27 and January 31 observers reported almost 50 avalanches in the Northern Mountains.

Favored areas in the Central Mountains received 15 to 30 inches of snow out of this storm with the highest amounts northwest of Crested Butte into the southwest corner of the Aspen zone. About a foot of snow was reported on the Grand Mesa. Other areas to the east generally received 8 to 10 inches of snow with decreasing amounts in the northern Sawatch zone. Observers in the Central Mountains reported 229 avalanches between January 27 and 31 with 120 avalanches large enough to bury, injure or kill a person. Most, 93, of these large avalanches were in the Gunnison zone.

The Southern Mountains got another good dose of snow out of this storm on January 30. The North San Juan Mountains zone generally picked up 7 inches of new snow with strong northwesterly winds behind the front. Areas in the South San Juan Mountains zone picked up about 10 inches of snow. Observers reported just over 100 avalanches from January 27 to 31 about half of those were large enough to bury a person (Destructive size 2 or larger).

Despite the strong finish in January we still ended up well below the median snowfall for January. Observers reported a total of 856 avalanches to the CAIC during the month. Almost 200 avalanches were human triggered. Amazingly only 8 people were caught in avalanches and fortunately nobody was killed in an avalanche accident.

The avalanche rose shows the total number of avalanches from January 1 to January 31 classified by avalanche trigger type. The rings show above treeline near the center near treeline in the middle and below treeline at the edge. Wedges show slope aspect with north at the top. The filtered row shows the number of avalanches that were large enough to bury or injure a person (Size D2 or larger) for each trigger type. The numbers indicate the total number of D2 or larger avalanches on each aspect at each elevation.

The weak layer that formed during the high-pressure in the middle of the month is still plaguing us into February and there aren’t any signs of avalanches letting up on this layer.

January tried to turn the corner, but just couldn’t make the transition.

December began with dry weather and a thin snowpack across Colorado’s mountains. Three storms swept across the state from the middle to the end of the month. Each storm spurred an uptick in avalanche activity. The CAIC recorded historic numbers of human-triggered avalanches in two separate week-long stretches during and after these storms.

Despite a snowy finish to the month with a foot of snow across the Northern Mountains and one to two feet in the Central and Southern Mountains, the snowpack remained shallow compared to typical years.

The CAIC recorded 1165 natural or human-triggered avalanches in December, of which 429 were large enough to bury, injure, or kill a person (D2 or bigger on the destructive scale). Of the 341 human-triggered avalanches, 62 were D2 or larger. There was an unusually large proportion of small avalanches (D1 on the destructive scale) triggered by people through the month, largely due to the low snowpack volume. As snow accumulated, the avalanche size increased. Twenty four people were caught in 23 different avalanches during the month. Seven people were buried, and tragically four people died. Those were the first avalanche fatalities in Colorado for the 2020-21 season.

The first ten days of December were dominated by a high-pressure blocking pattern, which extended the dry weather streak that began in late November. This dry weather resulted in a period where the upper portion or entire snowpack developed into cohesionless faceted grains. Toward the end of this period, loose snow avalanches gained considerable mass as they entrained more and more of the faceted snow. Warmer daytime temperatures in the Central and Southern Mountains formed thin crusts on lower elevation, south-facing slopes. The weak snow and thin crusts would become problematic once they were buried by subsequent storms. With the exception of two days where winds increased avalanche danger in the Sangre de Cristo zone, the avalanche danger remained LOW (Level 1 of 5) for the CAIC’s ten forecast zones from December 1 until December 10.

The first in a series of storms began on December 10. Over the next three days, the Northern Mountains would pick up about six inches of snow, the Central Mountains about a foot, and the Southern Mountains about nine inches. Winds were strong during and after the snowfall. This storm quickly ramped up avalanche activity and the avalanche danger. A forecaster described the “rude winds” blasting and ravaging snow near and above treeline. The CAIC issued a statewide Special Avalanche Advisory on Dec 12 to warn backcountry travelers about the abrupt change in avalanche conditions.

The CAIC recorded 93 human-triggered avalanches between December 10, and 17, the largest number of human-triggered avalanches recorded in a one week period in 10 years of CAIC data records. Luckily, due to the shallow snowpack, only three of these avalanches were large enough to bury or injure a person (D2 or larger).

There were no avalanche incidents during the stormiest period, but three people were caught in avalanches on December 14, 15, and 17, respectively. On December 15, a backcountry snowboarder was injured in an avalanche northwest of Crested Butte. That was one of the few large avalanches that occurred in this period.

The next snowy period began December 18 and finished on December 21, with about three to six inches in the Northern Mountains and roughly double that in the Central and Southern Mountains. The CAIC recorded the second largest number of human-triggered avalanches in 10 years during the week of December 17 to 23. There were 83 human-triggered avalanches, 19 of which were D2 or larger.

On December 18, a solo backcountry skier was caught, buried, and killed in an avalanche west of Crested Butte. The avalanche broke in the faceted snow that developed in November and early December. Another group backcountry skiing in the area realized the solo skier was late, and discovered him buried in the avalanche.

On December 19, two backcountry skiers were caught and killed in an avalanche southeast of Ophir. The pair were ascending low-angle terrain in the bottom of a large avalanche path known as the North Face of Battleship. Realizing the pair had not returned, a group of friends skied into the area and found the pair late that night. Again, the avalanche broke in the faceted snow that developed in November and early December. Only about 5% of avalanche fatalities in Colorado occur within two days of the previous fatality, so it was rare to have these tragic events so close together. By December 20, seven other people triggered and were caught in avalanches with less tragic consequences.

Two storms hit the Northern Mountains on December 23 and 27 both bringing a few inches of snow and strong winds. Though modest snow amounts, these storms were enough to overload the weak and shallow snowpack. Cycles of natural avalanches followed each storm. The CAIC did not receive reports of anyone being caught in avalanches after December 20 until tragedy struck again on December 26. That afternoon, a backcountry skier left a trailhead north of Berthoud Pass. He planned to climb a ridge and descend to First Creek, the next trailhead north, where his family would meet him. He never arrived. Search and rescue volunteers found the skier buried in avalanche debris. The avalanche was fairly small, but ran through a narrow cliffy chute. It, too, broke in the old snow near the ground.

The First Creek fatality was the fourth and final fatal avalanche of December. Seven more people were caught in avalanches before the month ended. Most of those involvements came in the last three days of the month, when a storm impacted all of the Colorado mountains. The Northern Mountains, again, only received a few inches of snow but it was sufficient to trigger another avalanche cycle. In the Central Mountains, snow added up to a foot or more across much of the Gunnison, Aspen, and Sawatch Zones. Twelve to 20 inches of snow fell in the Southern Mountains.

Avalanche danger spiked, and on December 29 the CAIC issued Avalanche Warnings for all zones in the Central and Southern Mountains. The CAIC recorded 427 natural and human-triggered avalanches in the four days between December 28 and 31, more than a quarter of all avalanches recorded in the month. Avalanches were deep, wide, and destructive. The dangerous conditions would last into early January.

Despite the snowy finish, December was a dry month. The statewide snow water equivalent (SWE) was only 76% of the 30 year median. Most SNOTEL stations were well below typical amounts at the end of the month. The exceptions were stations Sangre de Cristo Range and eastern San Juans Mountains, where the fall pattern of greater than usual snowfall continued into December.

The CAIC issues avalanche danger ratings based on the North American Avalanche Danger Scale. This scale contains five levels from Low danger (Level 1) to Extreme danger (Level 5). During certain avalanche conditions, we may issue a special product in addition to the danger rating. The three special products we may issue are:

• Avalanche Watch
• Avalanche Warning
• Special Avalanche Advisory

These products have different applications and we issue them to catch your attention for different reasons. The products are clearly displayed on the home page map if you hover over a forecast zone. The products are also displayed as headline banners in the backcountry avalanche forecast.

Avalanche Watches and Warnings are related and based solely on current and expected avalanche hazard. We issue them when the avalanche hazard is, or will be, High (Level 4) or Extreme (Level 5).

Special Avalanche Advisories are different from watches and warnings. They are based on concerns that people are at increased risk of being harmed by an avalanche. We consider the avalanche conditions and the number of people that we expect in the backcountry. We’ll issue a Special Avalanche Advisory when we are worried that you have an increased chance of getting in an avalanche accident, but the avalanche danger isn’t going to be High or Extreme.

Avalanche Watch

An Avalanche Watch means that there is a good chance we will issue an Avalanche Warning in the near future (around 24 hours).

Our goal is to issue an Avalanche Watch the day before an Avalanche Warning. Although this is the goal, at times we may issue an Avalanche Warning without issuing a Watch. We might also issue an Avalanche Watch and no subsequent Avalanche Warning. Remember, these are forecasts and sometimes the avalanche danger rises rapidly. Other times we expect it to rise, but the storm fizzles and the danger never reaches the criteria for High.

What you should do– Be prepared! Re-evaluate your backcountry travel plans for the following day. Consider planning alternate safe routes for multi-day trips should conditions worsen. Check the avalanche forecast at colorado.gov/avalanche for the latest updates.

Avalanche Warning

An Avalanche Warning means we have very dangerous avalanche conditions. The avalanche danger is High (Level 4 of 5) or Extreme (Level 5 of 5) and large natural avalanches are either happening or are expected to happen during the forecast period. During this warning period, human-triggered avalanches are very likely.

What you should do– Take action! Avoid avalanche terrain. If you are traveling in the backcountry during a warning, be aware of your surroundings and avoid crossing underneath avalanche paths. Plan any backcountry outing very carefully to steer clear of avalanche terrain and give avalanche paths a wide berth.

Special Avalanche Advisory (SAA)

A Special Avalanche Advisory means the avalanche danger is not High or Extreme (Levels 4 and 5 of 5), but we have the conditions for a dangerous avalanche accident. We might issue an advisory to alert you of rapidly changing avalanche conditions or potentially dangerous conditions with many people at risk. For example, the CAIC could issue a SAA if a big storm is going to roll through during a holiday weekend. We might also issue an SSA if large, human-triggered avalanches are likely over a weekend with deep powder and bluebird conditions.

What you should do– Exercise caution. Evaluate slopes that are mentioned in the advisory with extra caution. For example, the SAA may talk about Persistent Slab avalanches breaking wider than expected and being touchier than expected on north and northeast-facing slopes. In this situation you would want to factor in a wider margin for safety while trip planning.

by Brian Lazar

Our first reported natural avalanche of the 2020-2021 season was associated with a healthy early September snow storm. After this single, small loose-snow avalanche in the Sangre de Cristo Range, the snow that fell in September almost completely melted away. A small storm in the second week of October added a little more to the snow cover, but our seasonal snowpack didn’t really begin to develop until we received a storm on October 24 to 26. This storm deposited 6 to 10 inches of snow across most mountain areas, with a little more in a few localized areas. Post-storm winds built stiffer slabs along ridgelines, and we closed out the month of October with the first report of a skier-triggered avalanche for the season near Breckenridge.

November had three storm events, and each produced an uptick in avalanche activity. The CAIC recorded 141 avalanches during the month, though only four of them were large enough to bury a person. Despite few areas with enough coverage for on-snow travel, seven people were caught in avalanches.

The first week of the month was dry and sunny. This melted the October snowfall on all but northerly-facing slopes at higher elevations. The snow that survived grew weak and faceted before the first storm arrived on November 7.

The first storm dropped 6 to 8 inches of dense snow across the Northern Mountains. This wasn’t quite enough to obscure the ground cover on most slopes, and we didn’t record any avalanche activity across the Northern Mountains region.

The Central Mountains picked up 6 to 15 inches of snow, favoring areas near Independence and Schofield Passes. With Highway 82 over Independence Pass still open, people had relatively easy access to high-elevation slopes. Three people triggered and were caught in small avalanches in Mountain Boy Basin over a two-day period. We recorded several small natural and rider-triggered slab avalanches across the rest of the Central Mountains.

The Southern Mountains were the clear winner from this first November storm, picking up 1 to 3 feet of snow between November 7 and 9. Coal Bank and Wolf Creek Passes received 4 to 5 inches of snow water equivalent (SWE). This storm helped to build the snowpack in the Southern Mountains faster than in the rest of the state, and this difference still remained significant through the end of the month. Although triggered avalanches were limited, we did record several skier-triggered avalanches near Red Mountain Pass and around Silverton.

After a four-day dry spell, the second storm of the month arrived November 13. This was a fast-moving storm that favored the Northern Mountains and was more notable for ferocious winds rather than ample precipitation. Remote weather stations recorded wind gusts approaching 100 mph statewide, and this event left most windward slopes scoured to the ground with stiff and discontinuous slabs plastered onto lee slopes. This event produced the distribution of our Persistent Slab avalanche problem for weeks to come, with stiff slabs most prominent on near and above-treeline, northerly and east-facing slopes.

The Northern Mountains picked up 6 to 12 inches of snow, and we recorded a dozen small slab avalanches between November 13 and 17, including a close call on Berthoud Pass on November 15. Fortunately the rider who triggered this avalanche was able to ride off the slab and avoid being caught up in the moving debris.

The Central Mountains generally received 3 to 6 inches of snow with areas near Crested Butte getting as much as 10 inches. This modest load spurred a bit of avalanche activity, mostly confined to small avalanches triggered by ski patrols using explosives. A notable skier-triggered avalanche in the Sawatch Range on November 13 provided a great illustration of our developing slab-over-persistent weak layer concern.

The Southern Mountains largely missed out on this mid-month storm, and only picked up a few inches of snowfall. They did not miss out on the wind, which redistributed the snow cover like the other mountain regions.

The last storm of the month arrived just prior to Thanksgiving Day. This one brought heavy snow to the Southern Mountains, including a nice upslope snow event in the Uncompahgre Gorge, and moderate snowfall further north. This spurred the most pronounced uptick in avalanche activity of the season with dozens of reported avalanches during and immediately following the storm. Again, all but one of these were small (less than D2 in size).

The Northern and Central Mountains picked up around 5 to 8 inches of snow in most places between November 22 and 25. We immediately saw an uptick in avalanche activity. Most of these slides were small, but a rider triggered one of the larger avalanches of the season near Berthoud Pass on November 25. On that same day, a skier triggered a small avalanche near Montezuma and took a short ride before arresting himself on the bed surface.

The Southern Mountains did the best from this storm arriving with warm southwest flow. The storm ended with cold air and just the right wind direction to generate more than a foot of snow on the north side of Red Mountain Pass. Avalanche activity perked up as it did elsewhere, and the day before Thanksgiving (November 25) turned out to be an active day in the Southern Mountains as well. A skier was caught and carried in a small avalanche in the Grandad Couloir near Red Mountain Pass. The skier was able to self arrest on the bed surface after getting knocked over, but lost one ski and one pole. Nearby, another skier triggered a soft slab avalanche and was able to ski out of the moving debris before being taken for a ride.

We ended the month with cold, clear conditions and the faceting process kicking into high gear. Small avalanches continued to trickle in through the end of the month, but there were no more reports of people being caught. Snowpack was below 30-year normal SWE, except for the Upper Rio Grande Basin, which still held ample snowpack from the nearly 5 inches of SWE it picked up in the first storm of the month.

The forecast going into December called for above average temperatures and below average precipitation.

Ethan Greene and Spencer Logan

News reports and social media threads about avalanche accidents often include some discussion of people’s experience level. The people involved in the accident are commonly described as “expert skiers” or “experienced snowmobilers”, but the single label can conflate someone’s riding skills and avalanche experience. Peers sometimes proclaim the group displayed a significant lack of experience, understanding of avalanche phenomena, or implementation of common safety practices. Occasionally someone presents the argument that only people with avalanche experience and training are caught in avalanches. We decided to dig a little deeper into the avalanche accidents in the 2019-2020 season, and take a closer look at the avalanche education and experience levels of people involved in these events. The onset of the COVID-19 pandemic also provided an opportunity to look at accidents before and after the shutdown in the spring of 2020.

Avalanche Accident Tracking in Colorado

The Colorado Avalanche Information Center (CAIC) has been documenting avalanche accidents in Colorado for decades. Over the years the effort has expanded from fatal accidents to include all avalanche involvements. Basically, we try to collect some information any time someone is caught, carried, or buried in an avalanche. We learn about these events from reports sent to us by the public, connections with county sheriff’s offices or search and rescue groups, media articles, threads we see on social media, talking to people at the grocery store or post office, and sometimes just rumors we hear from our friends and families. We typically reach out to the people involved, try to verify some details, and gather whatever additional information we can. When someone is killed in an avalanche we conduct a more detailed investigation and interview as many witnesses and survivors as possible. You can read those reports here and see a summary of what we’ve collected over the last 20 years in Figure 1.

Figure 1: Number of reports to the Colorado Avalanche Information Center of people caught and killed in avalanches during the last twenty Colorado avalanche seasons.

What We Did

Other researchers have examined the education and experience levels of people involved in avalanches, but they focused on the victim’s avalanche training and self-assessed avalanche experience (McCammon 2000, Zweifel et al. 2012, Martensson et al. 2013). Because we don’t interview everyone involved in every accident, we don’t know all the avalanche classes taken by all the people in the group or their self-assessed avalanche skills. As such, we developed alternative tools to categorize a person’s avalanche experience.

For avalanche education level, we created the Avalanche Education Level (AEL) scale (Table 1), based on the American Avalanche Association’s course progression. The AEL just looks at if someone either has or has not reported taking an avalanche class at a particular level.

Table 1. The Avalanche Education Level (AEL) scale we used to categorize people’s education levels and brief descriptions of the courses.

AEL (codes used in other tables and graphs)	Reported Education
Unknown (Unk)	Unable to categorize
None	No formal avalanche training
Awareness (Aware)	Awareness or introductory avalanche education
Level 1 (Lev 1)	Three-day course including instruction in classroom and field
Level 2 (Lev 2)	Advanced training for recreationalists
Professional (Pro)	Professional-level courses with structured evaluation

We also developed the Inferred Avalanche Experience Level (IAEL) scale (Table 2) to rank avalanche experience from indirect evidence like an observation report, interviews, or descriptions from other people. We based the IAEL on the National Institutes of Health’s Competencies Proficiency Scale (CPS). The CPS is a human-resources tool that allows interviewers to rank a candidates’ experience. It is also used as a self-assessment to see where your experience places you in your career progression. The CPS has parallels with the Dreyfuss Learning Model (Dreyfuss and Dreyfuss 1980) that allows researchers to assess how well people learned a set of skills or knowledge through training and instruction. Researchers in Canada (St Clair 2019) used similar models to assess avalanche forecast users. You may have taken their survey a few years ago, or seen one of their presentations at an annual Colorado Snow and Avalanche Workshops (CSAW). None of the previous models were directly applicable to what we tried to do, but did allow us to develop a scale that relates to other assessment efforts. At each level, we developed examples of evidence to help us infer experience. We used evidence like statements from the group, their use of technical language in an observation, descriptions of pre-trip planning, and if they used safe travel practices. The IAEL is a subjective scale, but one that is relatively repeatable between researchers.

Table 2. The Inferred Avalanche Experience Level (IAEL) scale and some of the guidance we used to categorize people’s experience.

IAEL (Codes used in other tables and graphs)	Guidance
Unknown (Unk)	Unable to categorize
None	Report came from a party not involved in the avalanche Statement from reporting party that involved party “didn’t know what they were doing” or “had no idea”
Beginner (Begin)	Involved party reported the avalanche Mention of checking or using the avalanche forecast Demonstrated basic travel practices (e.g. exposing one person at a time to avalanche hazards)
Intermediate (Int)	Party demonstrated skills learned in a Level 1 recreational avalanche course Report used basic terminology correctly Evidence of pre-trip planning
Advanced (Adv)	Trip planning discussed or documented Snow profiles or tests conducted and interpreted Adjusted plans based on field observations
Expert (Exp)	Discussion of avalanche or terrain use concepts showed a high level of understanding Evidence of multiple seasons of applied skills Recognized as “person to ask” among peer group
Authority (Auth)	Professional expert with experience in multiple professional roles Developed new research, references, or tools

We used the definitions in Snow, Weather, and Avalanches: Observation Guidelines for Avalanche Programs in the United States (American Avalanche Association, 2016) to define the types of avalanche involvements and select events for the dataset. We identified as many people as possible involved in these avalanche incidents. If there were five people in a party, but only one person caught, we determined individual IAEL values for each of the five people. While imperfect, this allowed us to include people who were not caught in the avalanche, but participated in the event and decisions made by the group.

We applied the AEL and IAEL scales to all the people we identified. We used all information the CAIC gathered, from detailed interviews and accident reports to brief observations submitted by the public. Some involvements were reported second-hand, with no information directly from the parties involved. The AEL and IAEL scales allowed us to assign levels to people when there were different amounts or different types of data available.

We used the Tier 1 avalanche danger rating to examine avalanche danger relevant to avalanche incidents. The Tier 1 rating is the highest avalanche danger level issued for a specific place and time. It’s displayed on maps of avalanche danger and used as the overall danger for a forecast region. The CAIC issues forecasts with different spatial extents depending on the time of year, and the Tier 1 rating allows for consistent comparisons between different days in the forecast season.

Significant impacts of the global COVID-19 pandemic began in Colorado in mid-March 2020. To examine potential changes in patterns of avalanche involvement, we chose 13 March 2020 as the pre- and post-pandemic division. On or around that date, cities and counties began imposing a patchwork of travel restrictions and public health rules. The State of Colorado closed ski areas and other public venues to reduce the virus transmission. CAIC staff and other professionals noted a significant increase in backcountry use following the closures.

What We Found

The CAIC documented 86 avalanche incidents during the 2019-20 season, and we identified 126 people involved in those incidents. There were 88 people caught and carried in moving avalanches, including six people fully buried and six people killed. There were eight people who triggered avalanches but were not caught, and 30 people not touched by moving debris. We identified gender for 76 people, 63 males and 13 females. There were 86 human-powered backcountry tourers, 13 motorized users, and a handful of hikers and climbers, as well as other activities.

We categorized all 126 people with the AEL and IAEL (Table 2). We were able to assign an AEL to 31 people. Of those, 29% appeared to have no formal avalanche education and 29% had taken a Level 1 avalanche class. Of the people who had taken a Level 1 avalanche class, five of them were involved in two separate incidents that resulted in avalanche fatalities. That may indicate a selection bias. CAIC investigators try to collect avalanche education levels when investigating fatal avalanches. Education levels were much less frequently available when people self-report avalanche involvements.

We assigned IAEL to 89 people. Fifteen percent of people were categorized as beginners, 25% intermediate, and 47% advanced. We saw the expected correlation with AEL and IAEL (Table 3)–the more experienced a person was with avalanches, the more formal education they tended to have. There were four people with advanced experience that had not taken formal avalanche classes, a reminder that education is important but not the only way to gain knowledge. Likewise, we found a range of inferred avalanche experience for people who had taken a Level 1 avalanche class. Education is important but not a substitute for applied experience.

Table 3. Counts of IAEL (horizontal) and AEL (vertical).

	Unk	None	Begin	Int	Adv	Exp	Auth	Totals
Unk	37		10	18	28	2		95
None		3	2		4			9
Aware			1	2				3
Lev 1				2	6	1		9
Lev 2					2			2
Pro					2	4	2	8
Totals	37	3	13	22	42	7	2	126

Most people involved in avalanches had intermediate or advanced levels of experience, which is consistent with previous research (McCammon 2000, Tase 2004). McCammon (2002) found that avalanche education did not reduce avalanche exposure. Instead, our results suggest people were using their training and experience to spend more time traveling in avalanche terrain, or traveling during more avalanche-prone conditions.

The distribution of AEL differed significantly (p<0.05) prior to and post pandemic-related closures. The proportion of people that completed a Level 1 avalanche class and were involved in an incident increased after the pandemic closures. On the other end of the education spectrum, we identified eight professionals involved in avalanches in the 2019-20 season, five who were caught. All five of the professionals caught occurred in avalanches prior to the pandemic closures, and three were ski patrollers caught in avalanches during early season avalanche mitigation. Only one professional was involved in an avalanche incident post pandemic closures, and they were not working when the incident occurred.

Likewise, there was a significant (p<0.01) change in the IAEL of people involved in avalanches before and after the pandemic-related closures (Figure 2), with the proportion of people involved shifting towards Advanced backcountry travelers after March 13. The proportion of Beginner backcountry travelers did not increase after March 13. We don’t know why this occurred, but there’s some anecdotal evidence that may help explain the shift. As recreation increased after pandemic closures of ski areas and other activities, easily-accessible areas became crowded and tracked up. More skilled recreators used those skills to push into less-familiar terrain or explore new areas. Like McCammon (2004) showed, they were using their skills while accepting an increased avalanche exposure. Some observers reported an “increase in risky behavior” or people “taking more avalanche risks.” These are very subjective observations, but consistent with research on increased risk acceptance in stressful situations (See Sapolsky 2017 for a summary). The uncertainty of a global pandemic is certainly a stressful situation.

Figure 2. Inferred experience levels, by percent, for people involved in avalanches in 2019-2020 avalanche season. The gray curve shows experience levels for the entire season. The light blue and dark blue curves show experience levels pre- and post- pandemic related ski area closures around March 13. The shift to more experienced people involved in avalanches after March 13 is statistically significant.

In Colorado, most avalanche accidents occur when the avalanche danger rating is either Moderate (Level 2) or Considerable (Level 3) (Logan and Greene 2018). This was also true during the 2019-2020 avalanche season with 60% of the incidents occurring at Moderate (Level 2) and 30% at Considerable (Level 3). An important point is that the CAIC issued a Moderate (Level 2) rating for 68% of forecast days in 2019-20. For a better comparison of incidents and danger ratings we looked at the ratio of the number of incidents at a Tier 1 danger rating to the total number of days with that Tier 1 danger rating (Figure 3).The number of incidents that occur at a Considerable (Level 3) danger rating is disproportionately large relative to the number of days that danger rating is issued. The proportion of avalanche incidents at Considerable (Level 3) danger to the total days with that danger rating is even more notable when considering the pre- and post pandemic periods. While half of the incidents at Considerable (Level 3) occurred before the pandemic related closures, the other half occurred after the pandemic shutdown even though only 17% of the forecasts between March 14 and May 31 had a Tier 1 danger rating of Considerable (Level 3). The comparative ratios are 0.06 before, and 0.16 in the post-pandemic period. The ratio for incidents at Considerable (Level 3) post-pandemic indicates a very high rate of incidents on days with relatively dangerous avalanche conditions. Like the shift we observed in IAEL, the number of incidents at Considerable (Level 3) after March 13 suggests that backcountry travelers were accepting greater avalanche exposure during hazardous periods.

Figure 3: The ratio of the number of incidents at a Tier 1 avalanche danger rating compared to the number of forecast days with the Tier 1 avalanche danger rating during the 2019-2020 avalanche season. The light blue and dark blue bars show the ratios pre- and post- pandemic related ski area closures around March 13. The Tier 1 rating is the highest single rating for any area issues for a 24 hour period.

Why Should We Care?

These results add to the ongoing discussion about education, experience, and avalanche accidents. Our approach provides a novel way to look at the experience level of people involved in avalanches, but there are also some limitations to keep in mind. First, our dataset is relatively small, consisting of a single season in Colorado and just the avalanche involvements reported to the CAIC. Second, our dataset is biased, as it only includes people involved in avalanches. The people who successfully avoid avalanches, with and without formal training and years of experience, are not included. Despite these limitations, this work provides an opportunity for all of us to think about who is getting involved in avalanches, how each of us might fit in that group, and hopefully how we can avoid a serious accident.

Nearly 40% of the people caught in an avalanche or in a group with someone caught in an avalanche, had taken a Level 1 avalanche class. According to our IAEL, about 70% had intermediate or advanced avalanche experience. This begs the question: Does formal, field-based training or avalanche experience increase or decrease your chance of getting caught in an avalanche? This study cannot answer that question. People that invest in avalanche education and gain experience in the mountains typically do so because they spend time in avalanche terrain, which increases their exposure to avalanches. In aggregate, the additional exposure may offset the application of risk-reduction strategies. Merging the benefits of careful terrain choices and snowpack analysis with the increasing exposure as the number of days in the field climbs is a challenging problem. We will leave those analyses to a talented and well-funded research group, but we are eager to hear what they find out.

Last spring the impacts of COVID-19 produced a dramatic increase in backcountry recreation. Based on the increased use of public lands over the summer, and the increases in sales of winter backcountry equipment, the upcoming winter promises more of the same. Our comparison of pre- and post-COVID periods suggests we may not see an increase in avalanche accidents driven solely by a flood of new users. Clearly the conditions that lead to an increase in avalanche accidents involve the interaction of multiple factors: more people in avalanche terrain, more use in easily accessible areas, more people moving into new areas looking for solitude or fresh snow, changes in the distribution of education and experience, and a myriad of other factors.

What should we do?

This project suggests we should all take a hard look at the assumptions we make about ourselves and our riding partners. Are we using our experience and skill to make good decisions, or are we just lucky? Are we correctly identifying avalanche hazards, the terrain where they exist, and making choices to reduce our risk? Or are our decisions based on experience built by a series of positive-feedback events and emotions driven by our pleasure-seeking brains. One strategy is to read and discuss accounts of avalanche accidents. To get the most benefit we need to think about what those people were experiencing as well as similar situations we have faced. A common tendency is to look for reasons why we would have done something different or why our education or experience would have produced a different result. This tendency, known as the blind-sight bias (Pronin 2008), can limit our ability to avoid a similar outcome when faced with similar circumstances.

We started this project to help us understand how people are interacting with avalanches in Colorado, and how our work can help people enjoy the snow and avoid getting into trouble. The reports we get, from people in the public and private sectors, allow us to provide descriptions of individual accidents as well as look for trends in a larger group of events. There could be more new users in the 2020-2021 season and we’re looking for ways to help them learn about avalanche safety, while continuing to provide good information and education for more experienced users. Backcountry users in Colorado are diverse. There are a lot of them, they are in a lot of different places, they have a wide range of experience and education, and they are participating in a variety of activities. We hope we are providing a service that helps you. Please read the avalanche forecast before you go into the backcountry. Take the Friends of the CAIC’s Forecast Pledge and challenge your friends to do the same. Get out into the snow and when you get back, tell us what you saw. Most importantly, have a fun and safe 2020-2021 avalanche season.

References

American Avalanche Association, 2016 Snow, Weather, and Avalanches: Observation Guidelines for Avalanche Programs in the United States (3rd ed).
https://www.americanavalancheassociation.org/swag

Dreyfuss, S. E., and Dreyfuss, H.L. 1980. “A Five-Stage Model of the Mental Activities Involved in Directed Skill Acquisition” http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA084551&Location=U2&doc=GetTRDoc.pdf

Logan, S. L., and Greene, E. 2018. Forecast avalanche danger, avalanche activity, and avalanche accidents in Colorado, USA, winters 2014 to 2018. International Snow Science Workshop Proceedings 2018, Innsbruck, Austria. https://arc.lib.montana.edu/snow-science/item.php?id=2710

Maartensson, S., Wikberg, P, and Palmgren, P.. 2013. Swedish Skiers Knowledge, Experience and Attitudes Towards Off-Piste Skiing and Avalanches. International Snow Science Workshop Grenoble – Chamonix Mont-Blanc – October 07-11, 2013 https://arc.lib.montana.edu/snow-science/item.php?id=1822

McCammon, I. 2000. The Role of training in recreational avalanche accidents in the United States. Proceedings of the 2000 International Snow Science Workshop, October 1-6, Big Sky, Montana. https://arc.lib.montana.edu/snow-science/item.php?id=704

McCammon, I. 2002 . Evidence of Heuristic Traps in Recreational Avalanche Accidents. 2002 International Snow Science Workshop, Penticton, British Columbia. https://arc.lib.montana.edu/snow-science/item.php?id=837

National Institutes of Health. Competencies Proficiency Scale. https://hr.nih.gov/working-nih/competencies/competencies-proficiency-scale

Pronin, E. 2008. “How We See Ourselves and How We See Others”. Science. 320 (5880): 1177–1180.

Sapolsky, Robert M. 2017. Behave: the biology of humans at our best and worst. Penguin Books, New York.

St. Clair, A. 2019. Exploring the Effectiveness of Avalanche Risk Communication: A Qualitative Study of Avalanche Bulletin Use Among Backcountry Recreationists. MS thesis, Simon Fraser University.

Tase, J.. 2004 Influences on backcountry recreationists risk exposure to snow avalanche hazards. MA thesis, University of Montana

Zweifel, B., Techel, F., and Bjork, C. 2012. Who Is Involved In Avalanche Accidents? Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska https://arc.lib.montana.edu/snow-science/item.php?id=1586

Governor Jared Polis issued a Safer-at-Home order on April 27, 2020. Coloradans can participate in outdoor recreation while wearing a mask, maintaining a distance of at least six feet, with no more than 10 people, and choosing a location that is within 10 miles from their home. These steps will help us slow the transmission of the virus and maintain healthy activities that strengthen your physical and mental health.

Many of Colorado’s counties have issued public health orders that affect travel and recreation. You can find information from Colorado’s counties here. Please respect all state, county, and local health travel orders when considering backcountry recreation.

If you are recreating, please do so responsibly. This includes following the Safer-at-Home guidance, not taking actions that risk pulling emergency service workers away from the important work they’re doing, or compromising their ability to continue that work. You can find more information from the Department of Natural Resources here.

“Our goal at the CAIC is to provide critical avalanche safety information for people recreating in the Colorado mountains, government groups at all levels, and CDOT as they work to mitigate the avalanche hazard above the State’s transportation system. We understand how important outdoor activities are for people’s mental and physical health in these uncertain times. We want people to be safe and responsible in all of their outdoor pursuits” says CAIC Director Ethan Greene.

The Colorado Avalanche Information Center will continue to provide daily weather and avalanche forecasts to support emergency services, increase safety on state and federal highways, and provide good information to help people if they choose to travel in the backcountry.

Please consider the following when deciding whether or not to engage in backcountry travel:

• If you are sick, stay home – Follow CDC guidelines and avoid spreading the virus to others.
• Stay close to home – Limit travel to trailheads as much as possible. Use the backcountry areas near where you live. Avoid travel to communities where you are not a resident.
• Know Before You Go
• Know the public health orders that affect your plans. Look at covid19.colorado.gov and check with the local government for any restrictions.
• If you don’t have avalanche rescue gear, avalanche training, and know how to use and interpret the avalanche forecast, do not go in or near avalanche terrain.
• Keep a social distance from others – Maintain the legally-mandated safe distance of six feet or more from other parties.
• Avoid travelling in high-risk and remote terrain and consider avoiding all avalanche terrain – Rescues stemming from avalanche incidents or accidents may require extensive resources. Colorado Search and Rescue teams are prepared and ready to respond, but could become overloaded if the number of calls increases and the number of available responders decreases. Being responsible outdoors can also help prevent additional burdens on our healthcare system.
• Avoid times and places of high use – Avoid creating large crowds and groups at popular trails or outdoor areas. Spread out and avoid times of highest use. Use COTREX to discover and explore other local trails in your area to help disperse traffic.
• Closed ski areas are backcountry – All Colorado ski areas are closed (some still allow uphill travel). The ski patrol is not available for emergency response or rescue. Snow safety teams are not mitigating the avalanche hazard. Conditions at the ski area are not safer than traditional backcountry areas. Travel in them like you are in the backcountry.
• If you go, get the forecast first and tell us what you see when you return home! CAIC is still issuing daily avalanche safety products. With professional operations such as ski areas, cat ski operations, and guide companies closed, the CAIC is missing a crucial source for observations. If you do go into the backcountry, please submit an observation via the web or mobile app. Even if all you have to report is that you did not see any avalanches or that you did not see any signs of instability, please take the time to send that important info!

If you are choosing to recreate in the mountains, a critical thing to remember is that your actions may impact others. We need to balance our risk in the backcountry while considering the consequences should we trigger an avalanche. Do not expose others to risk without their consent. This includes recreating above other people or open roadways. Consider the burden you might place on our already strained search and rescue and health care systems should someone in your group get hurt or worse. Please enjoy the backcountry safely and keep our communities and fellow backcountry tribe members in mind when you consider your terrain choices.

Updated April 29, 2020

By Spencer Logan

March has been an exceptional month in Colorado the last couple years. In March 2019, there was an incredibly widespread and destructive avalanche cycle. Avalanches ran larger than they have in 100 or more years. In March 2020, there was a widespread global pandemic. A virus had a larger global impact than any have in 100 or more years. That had little impact on avalanches, but did have a huge impact on Colorado communities and outdoor recreation. The human impacts of the pandemic arrived as avalanche conditions changed, and the confluence led to an interesting series of avalanche involvements and discussions about backcountry travel and rescuer’s risk.

March began with a large north to south difference in Snow Water Equivalent (SWE). Many SNOTEL sites in the Northern Mountains began the month with 150 to 200% of median (1981-2010) SWE. The Central Mountains started near or above the median, while most sites in the Southern Mountains were near or below median SWE. Snowfall through March favored the Southern Mountains, and reduced these disparities. All mountain regions were near or above median SWE by the end of month.

The CAIC recorded 716 avalanches in March. Thirty percent of these avalanches occurred in the Gunnison Zone, and 20% in the North San Juan Zone. Two hundred and forty, or 33% of the avalanches, were human-triggered.

The CAIC documented 25 people caught in 23 separate avalanches throughout the month. Seventeen of the incidents occurred in the North San Juan zone, and thirteen of the 17 occurred in the second half of the month. Two backcountry riders were seriously injured, requiring Search and Rescue assistance against the backdrop of the coronavirus pandemic. Despite the large number of involvements, only those two riders were seriously injured and there were no fatal avalanche accidents.

Across the Northern Mountains,the first half of March could be characterized as warm and dry. Daytime temperatures climbed above freezing almost every day. There were a few dashes of snow, but it was not until March 20 that winter returned. Calendar spring started with a good strom, bringing a foot or more of snow and an inch or two of SWE. Winds were strong and gusty during and after the storm.

Persistent weak layers remained an issue throughout the month. Slabs stacked on top of layers of near surface facets, facet-crust combinations, and basal depth hoar. Following any of the snowfall events, winds drifted snow into touchy slabs. By the end of March, low elevations and sunny slopes began the transition to a warm surface snow. Wet loose avalanches became increasingly frequent.

On March 25, two backcountry snowboarders triggered a small avalanche in wind-loaded snow on a west facing slope above the Eisenhower Johnson Memorial Tunnels. As the avalanche ran downhill, it broke into deeper weak layers and eventually to the ground. This left debris piles 20 feet deep over the Tunnel access roads.

The Central Mountains fell in the middle of the statewide north-south gradient, and also had a west to east gradient in snowfall and avalanche activity. In the east and west, the Sawatch and Grand Mesa zones, respectively, had a relatively dry month with little avalanche activity. By the middle of the month, low elevations and sunny slopes were well on the way through the transition to a spring snowpack.

After a storm in the first week of the month, warm and dry weather dominated through March 20 in the Gunnison and Aspen zones. Small wet loose avalanches were common. Melt-freeze crusts formed on many slopes, sandwiching several thin layers of faceted snow. Snowfall began on March 20, and quickly produced a cycle of large avalanches followed by another storm and avalanche cycle to close out the month. Despite the number of avalanches recorded, there were no close calls with backcountry travelers reported. Low elevation, wet-loose avalanches did run onto county roads with minor impacts in the Aspen area.

In the San Juan Mountains, small storms at the beginning of March buried weak snow that developed in February. An emerging Persistent Slab avalanche problem began to take shape but overall the slab was shallow and not heavy enough to overload weak layers. Yet.

As early as March 2 the CAIC documented a skier-triggered slide in Bear Creek near Telluride that failed on the February near-surface facets. With each storm, the slab got slightly bigger and avalanches began to increase from D1’s to D2’s. On March 9, an experienced avalanche worker triggered an avalanche near Wolf Creek Pass, was caught, and buried to his waist. By March 13 the slab was big enough to push many northwest through northeast-facing slopes close to the tipping point and riders began triggering slides at all elevations large enough to bury, injure or kill.

On March 19 snowfall began, and several feet of snow would accumulate over the next several days. Moderate southwest wind accompanied the storms. Stability slowly decreased as the snow fell, and there were both natural and human triggered slides on deeper weak layers.This increase in avalanche danger coincided with the sugre of backcountry use after ski areas were closed to reduce the spread of the coronavirus. Many riders were caught off guard by this rising avalanche hazard after a relatively stable mid-winter period. Over half of the 146 avalanches reported occurred in the 11 day period of March 13 to 24.

Wind followed the snowfall and triggered a natural avalanche cycle with some of the largest avalanches of the season (2.5 and 3 on the Destructive Scale on March 26). On March 20, there were three close calls in Ophir. In one of the avalanches, both members of the party were partly buried; one of them with only one arm free allowing her to dig out her face and clear her airway. On March 24 a rider was seriously injured after an avalanche slammed him into a tree. A very speedy response by other backcountry groups, Ophir residents, and Search and Rescue saved his life. On March 31, a backcountry tourer was ascending when he triggered an avalanche. He, too, was slammed into a tree and seriously injured. Search and Rescue evacuated the tourer.

While not the only rescues that Search and Rescue groups responded to, the avalanche incidents received lots of attention from the news media. The rescues highlighted the need for SAR volunteers to take additional precautions to minimize coronavirus exposure. The incidents also highlighted the increased need for backcountry travelers to consider their potential impacts on others. The CAIC focuses on avalanches, and encourages backcountry tourers to consider the consequences of an avalanche. But with increased backcountry use and a rapidly changing societal response to the coronavirus, avalanches were just a portion of a larger discussion of risk and exposure.

On April 12, 2020 we will transition to our spring forecasting schedule. We will issue daily avalanche forecasts for three regions of the Colorado mountains by 4:30 p.m. through May 31, 2020.

Below is an outline of the regional products and how to use them.

1. You can find these products under the “Forecasts” menu option of the website. Links to these products will also be emailed out each afternoon and be available on the mobile app.
2. There are three forecasts:
   1. Northern Mountains (Steamboat & Flat Tops, Vail/Summit, and Front Range Zones)
   2. Central Mountains (Grand Mesa, Aspen, Gunnison, and Sawatch zones)
   3. Southern Mountains (North San Juan, South San Juan, and Sangre zones)
3. Each regional forecast contains a danger rating for tomorrow and a danger rating for the following day. The danger rating is the highest expected danger rating in the region for each day.
4. Each regional product contains a forecast summary that describes the type of avalanches you may see, areas of concern, and things to watch for as you are traveling in avalanche terrain.
5. Each regional product also has a tab with recent observations and weather data for that region. If you are in the mountains please Submit an Observation as the forecasters rely on those to get an accurate view of what is happening in the mountains throughout Colorado.

We hope you will find these products useful throughout the spring.

Click here to complete the survey

Stuck at home? Need something to do that can help your backcountry community?

The CAIC is helping and promoting a survey, in partnership with our colleagues across the US and in Canada, to help us improve backcountry forecast products.

The Avalanche Research Program at Simon Fraser University, Avalanche Canada and several U.S. Avalanche Centers are conducting an online survey to examine how backcountry recreationists—skiers, mountain snowmobilers, snowshoers and ice climbers—use public avalanche safety information. We are interested to hear from backcountry users of all experience levels. Our goal is to better understand how you process hazard and terrain information provided in public avalanche forecasts. The results of this study will offer important insight for improving avalanche safety information products in Canada and the United States.

Participants who complete the survey before May 15, 2020 will be entered in a draw for several cash prizes. Click here or visit https://avbullvis.avalancheresearch.ca/ to participate and for a chance to win cash prizes!

By Jason Konigsberg

Snow coverage in Colorado was fairly evenly distributed by the end of January. All Colorado river basins were at or above 100% of the normal median for Snow Water Equivalent (SWE). This changed in February. Persistent northwest flow brought consistent snowfall to the Northern Mountains and parts of the Central Mountains. SWE increases during February were 200% of the normal median for numerous Snotel sites in the Northern Mountains. The Sangre de Cristo range and Red Mountain Pass stayed close to 100% of monthly SWE increases while other areas of the Southern Mountains saw a very dry month.

The CAIC recorded 862 avalanches during the month, 122 of which were triggered by people. Eleven people were caught in avalanches, three partially buried, and tragically two people were fully buried and killed.

The first few days of February started warm and dry. The avalanche danger was Moderate (Level 2 of 5) in all ten zones on February 1 and the primary avalanche concern was triggering a small to large Persistent Slab avalanche. February 2 was the warmest day of the month and many mountain locations saw temperatures break the 40 F mark. Fremont Pass (11,400 ft) recorded a high temperature of 43 F. Schofield Pass (10,701 ft) a high of 47 F and Wolf Creek Pass (11,800 ft) a high temperature of 36 F. As temperatures subsequently cooled off, a crust formed on east through south-facing slopes. Plummeting temperatures on February 4 and 5 quickly faceted the snow around this crust. This crust-facet combination would become a major problem with additional loading.

The next loading event started on February 6. An Atmospheric River riding over a high-pressure system in the Pacific took aim at Colorado. The CAIC issued an Avalanche Warning for six zones in the Northern and Central Mountains on February 6, which continued through February 8. A period of intense snowfall began on February 6 and lasted through the evening of February 7. The northwesterly storm track favored the Northern Mountains and parts of the Central Mountains. This storm was one of the most intense 48-hour periods in recent memory. The Columbine Snotel, on Rabbit Ears Pass, recorded a 2.9” increase in SWE in 24 hours. This was the biggest 24 hour SWE increase at this Snotel since the site was installed in 1986. Other notable SWE increases included Copper Mountain and Independence Pass Snotels with a three-day increase of 2.6” and 2.5” respectively. These 3-day numbers were also a Snotel data record. Although this storm largely missed most of the Southern Mountains, portions of the North San Juan zone still picked up healthy snow amounts. Storm totals for Red Mountain Pass were about 2 inches of SWE, around 3 feet of snow.

As expected, we saw numerous avalanches during the storm associated with periods of high-precipitation intensity. As the storm cleared on February 8, it seemed that a lot of the evidence of natural avalanches was filled in by winds, obscuring the true extent of this avalanche cycle. Slopes that did not avalanche were left with a new and strong slab of snow resting on old weak layers. In some cases the 2 to 4 feet thick slab lay above both the weak layer that formed in early February and basal facets, or depth hoar, from October. Following the storm numerous avalanches broke on these weak layers in the Northern Mountains and the Sawatch and Gunnison zones.

CDOT mitigation efforts along I-70 and near Berthoud Pass on February 11 triggered a large avalanche in the Widow Maker slide path near Arapahoe Basin that buried US-6. Mitigation work also triggered another large avalanche in the Campground slide path near Berthoud Pass. This slide path put avalanche debris on US-40 for the first time since 1950. On February 13 CAIC and CDOT conducted helicopter mitigation work in Tenmile Canyon. Numerous large avalanches ran with powder clouds dusting I-70.

Northwest flow continued to generate snow through the middle of February for the northern half of Colorado. Consistent snowfall and several strong wind events led to spikes in avalanche activity. One of the most notable events occurred around February 14, causing another uptick in avalanche activity.

On February 15 , three motorized snowbikers north of Vail triggered a hard slab avalanche. All three riders were caught in the avalanche and two were fully buried and killed. This was the third and fourth avalanche fatality in Colorado this season. The avalanche likely failed on an old layer of faceted snow about three feet below the surface. This was most likely the weak layer that formed in early February during warm weather followed by very cold temperatures.

Another round of snow hit the Northern Mountains and parts of the Central Mountains on February 23 and 24. An intense band of snow set up in a line from Leadville to Breckenridge on the morning of the 23. Areas underneath this band saw 2 inch-per-hour snowfall rates with 8 to 10 inches in 5 hours. There wasn’t much wind during the snowfall and although the snow fell fast and furious, few avalanches were reported. This changed overnight on the 24 as wind increased dramatically from the northwest. The intense loading resulted in numerous natural avalanches. The most widespread activity was noted in the Sawatch Range but the largest and most notable avalanches were observed near Peak 1 in the Tenmile Range. The Peak 1 avalanche looked to be the largest avalanche in Colorado this season.


For the month of February, the Steamboat and Flat Tops zone had a lower avalanche danger than the other forecast zones in the Northern Mountains. The Steamboat and Flat Tops zone had a deeper and stronger snowpack at the start of the month. The early February storm produced abundant snowfall across the zone, but with a strong snowpack most of the avalanches were small. There were no reports of avalanches breaking on deeper weak layers during the storm or for the rest of the month. The CAIC rated the avalanche danger as Low (Level 1 of 5) for eleven days during the month. Increases in the danger were caused by precipitation and wind events, and associated new snow avalanche problems.

February was an active month for avalanches in the rest of the Northern Mountains and part of the Central Mountains. The Front Range, Vail and Summit County, Sawatch and Gunnison zones had similar avalanche danger ratings and avalanche problems most of the month.

Although the avalanche danger ratings in the Aspen zone were similar to the more active zones, there was much less avalanche activity. The number of avalanches reported decreased faster than in adjacent zones after the big February storm, and the last large avalanche in the Aspen zone was on February 8.

In the Southern Mountains, the avalanche danger was generally lower in February than it was in January. The San Juan Mountain zones went to Low danger for the first time this season on February 2. For the month, the North San Juan zone and the South San Juan zone were at Low danger 9 and 12 days respectively. Any days of higher danger were associated with small snowfall amounts coupled with wind-drifting, sometimes activating shallowly buried weak layers.

By the end of February the water content of the snowpack was above or near the normal median for most areas. The southwest corner of the state dropped below the long term median. In the deeper snowpack areas, weak layers improved and there were no reports of avalanches breaking near the ground for the last four days of February. The Southern Mountains ended the month with a shallower and weaker snowpack than on February 1. Although sunny slopes were beginning to transition to a springtime regime, the snowpack on shady slopes lost strength.

by Brian Lazar

Despite more modest snowfall than we saw across the state in December, we ended the first month of 2020 with the Snow Water Equivalent (SWE) over 100% of the long-term median across all of Colorado’s river basins. January had light and fairly continuous snowfall, characterized by several small to mid-size storms and interspersed with short dry spells. Crusts and weak layers formed in the upper snowpack during these dry spells. Each loading event of more than a few inches of snow spurred some avalanche activity. The month also saw several very strong wind events which dramatically altered the alpine landscape and redistributed snow in many areas.

The CAIC recorded 648 avalanches in December. One hundred and twenty nine of those avalanches were human triggered. Twenty-three people were caught in avalanches during the month, including 11 people in one week between January 18 and January 25. Five people were partially buried, 3 were injured, and tragically, one person lost their life when they were hit with a mix of falling ice and snow. This was the second avalanche fatality in Colorado of the 2019-2020 season.

The first storm of the month dropped 8 to 12 inches of snow from January 2 to January 4. This led to our first avalanche cycle of the month, including our first avalanche involvements. Avalanche incidents during this period were concentrated in the Northern Mountains. A skier triggered and took a short ride in a small avalanche on Loveland Pass on January 2. A similar incident occurred in Rocky Mountain National Park on January 5. Also on January 5, a skier triggered a small avalanche on Coon Hill on the west side of the Eisenhower Tunnel and was carried several hundred feet before coming to rest. A few days after the storm ended a CAIC forecaster triggered and took a short ride on the south side of Coon Hill as well. Fortunately, no one was buried or injured in these incidents.

We had a four to five day dry spell after Jan 5, along with very cold temperatures. This formed a very weak layer of near-surface facets in most mountain locations. This near-surface weak layer showed its potential to produce avalanches when the second notable storm system arrived in the second week of January. This storm dropped between 4 to 8 inches of snow in most mountain areas between the 10th and the 14th, with snow coming earlier in the San Juan Mountains and later in the Central and Northern Mountains. This modest loading event led to a fairly widespread avalanche cycle.

There were 35 reported avalanches in the Northern Mountains. Eleven of those avalanches were large enough to injure a person. Most avalanche activity occurred on north to east to south-facing slopes. We received reports of one partial burial near the Eiseman Hut on January 10. There were no other avalanche involvements during this second storm.

The CAIC recorded 49 avalanches during this time period in the Central Mountains, 31 of these avalanches were large enough to injure or kill a person. The CAIC also recorded 29 avalanches in the Southern Mountains all of which were large enough to kill or injure a rider. Similar to the Northern Mountains, most avalanches in the Central and Southern Mountains occurred on northwest to east to south facing slopes.

We had another dry spell from January 15 to 18, when our third notable storm system arrived. It wasn’t a big system to start, dropping only around 6 inches of snow in most mountain areas by January 19, but this was quickly followed by a bigger system on January 22 and 23, which added another 7 to 14 inches of snow. This one-two punch kicked off our most concentrated week of avalanche incidents during the 2019-2020 season.

The Steamboat area, which had seen little activity outside of small storm-snow avalanches up to this point, reported its first large skier-triggered Persistent Slab avalanche on January 19, breaking 3 feet deep on the January 9 layer. Between January 19 and 25, 8 people were caught and carried in avalanches in the Northern Mountains. Two partially buried. One of these was a climber in Rocky Mountain National Park who triggered an avalanche and was washed over a 50 foot cliff. Fortunately, this resulted in only minor injuries. A backcountry skier was also seriously injured after being caught and carried in a large avalanche near Jones Pass on January 22.

In this same week a skier was caught and carried in an avalanche in Red Lady Bowl above Crested Butte. In the Southern Mountains an ice climber was killed in the Uncompahgre Gorge on January 18 after an ice pillar broke loose, entrained small amounts of loose snow, and hit a climber with chunks of ice and snow, burying here in the creek below. This was the second avalanche-related fatality in Colorado of the 2019-2020 season. The week closed out in the Southern Mountains with a snowmobile triggered avalanche near Molas Pass that caught and carried a rider.

After January 25, Colorado saw another brief dry spell before our fourth and final modest storm system arrived on January 27. Once again the storm differed slightly in timing but was egalitarian in delivering around 7 to 14 inches of snow to most mountain areas through January 28. This kicked off yet another avalanche cycle and another round of avalanche incidents.

The CAIC documented 21 avalanches in the Northern Mountains during or immediately after the fourth storm. Nine of these avalanches were large enough to kill or injure a person. All of these avalanches occurred in the Vail-Summit and Front Range zones. Two people were caught in avalanches including an on duty patroller. There were 14 avalanches in the Central Mountains, 3 were large enough to kill or injure a person. A snowmobiler was caught and partially buried on January 20 near Kebler Pass west of Crested Butte. The CAIC received reports of 23 avalanches in the Southern Mountains. Thirteen were large enough to kill or injure a skier. Three people were caught in avalanches in two separate incidents in the South San Juan Zone.

We closed out January with only a few avalanches breaking near the ground. Most avalanches released in storm or wind-drifted snow, or on weak layers buried in the middle of the snowpack. Basal weak layers remained a concern in our thinner snowpack areas, but it was going to take larger loading events to see deep avalanches.

by Mike Cooperstein

The year ended with average to above average snowfall for the month of December across Colorado. Five storms during the month pushed the Snow Water Equivalent (SWE) to over 100% of the long-term median across all of Colorado’s river basins. The Southern Mountains received the most snowfall in December with areas around Wolf Creek Pass picking up almost 90 inches of new snow in the month of December alone. The new snow and periods of wind created a stiff slab over a weak layer of depth hoar near the ground and we started to see large natural and human-triggered avalanches breaking at the ground. The CAIC recorded 547 avalanches in December. Eighty-three of those avalanches were human triggered. The CAIC recorded sixteen riders that were caught in avalanches. Tragically, one of those avalanches resulted in a fatal avalanche accident. This was the first person killed in an avalanche in Colorado during the 2019-2020 season.

Five storms in the month of December 2019 brought us to above average snow and water for the season. This figure shows the basin wide percent of normal (percent of median from 1981 to 2010) snow water equivalent (SWE) across Colorado at the beginning of January.
December began with a few days of high-pressure, clear skies, and dry conditions. The next two weeks were a stormy period across Colorado with three storms hitting almost back to back to back from December 3 to December 16. Many areas in the Northern Mountains received 30 inches of snowfall in those 13 days. Breckenridge Ski Area received 43 inches of snowfall in the 3 days period from December 13 through December 16. Favored areas in the Central Mountains received around 2 feet of snowfall from December 3 to December 8 and then another 2 feet of snowfall from December 14 to December 16. Areas in the Southern Mountains received almost 40 inches of new snow as well in those 13 days with Wolf Creek Pass getting hit with 20 inches of snow in a 12-hour period on the night of December 16.
All of the new snow spurred a widespread avalanche cycle. Two hundred and ninety-five natural and fifty-five human triggered avalanches, large enough to kill or injure a person were reported to the CAIC in the first 16 days of the month.

	Natural Avalanches	Human-Triggered Avalanches
Northern Mountains	44	26
Central Mountains	191	16
Southern Mountains	60	13

This table shows the distribution of natural and human triggered avalanches large enough to kill or injure a person (D2 or larger) across Colorado from December 1 to December 16, 2019.
On December 8, a backcountry skier was caught, buried, and unfortunately killed by one of these large human-triggered avalanches. The accident occured on the Diamond Peaks in the Cameron Pass area of the Front Range zone. Many of these large avalanches were remotely triggered, which illustrated unstable the the threat from our Persistent Slab avalanche problem. Despite all of the new snow, the snowpack remained relatively thin across most of the state and most of these avalanches broke at the ground.

On December 1, 2019, a snowmobiler remotely triggered this avalanche in the Rollins Pass area in the Front Range zone. Observers reported cracking and collapsing and many remotely-triggered avalanches to the CAIC in the first few weeks of December.

A skier triggered this avalanche on Berthoud Pass, in the Front Range zone, on December 11, 2019.

This photo shows a remotely-triggered avalanche in the Vail and Summit County zone on December 12, 2019.

From December 17 until about December 23 a period of high pressure brought dry conditions with clear skies and unseasonably warm temperatures. Temperatures rose well above freezing in many areas. This built sun crusts on southerly-facing slopes and left weak, faceted crystals on the snow surface on north and east-facing slopes. These would become the weak layers for avalanches toward the end of the month. Riders continued to trigger avalanches that broke at the ground during this prolonged dry spell.

A snowmobiler remotely triggered this avalanche in the Never Summer Range, Front Range zone, on December 17, 2019. He was farther away than where this picture was taken when he triggered the avalanche.

A snowboarder unintentionally triggered this large avalanche in the Loveland Pass area on the border of the Front Range and Vail and Summit County zones on December 19, 2019.
Just before Christmas another storm moved over Colorado. On December 25 and 26 areas in the Southern and Central Mountains as well as the Vail and Summit County zone accumulated 12 to 16 inches of new snow. The Steamboat and Flat Tops zone and Front Range zone picked up 3 to 8 inches of snow. This snow fell on a weak snow surface in many areas. We continued to receive reports of large natural avalanches over Christmas; however, we were seeing many fewer avalanches break at the ground and many more avalanches break at the interface between the new and old snow.

A natural avalanche in the Wemuniche Wilderness in the South San Juan zone, December 26, 2019.
The final snow storm of the decade occurred from December 27 to December 29. Snowfall favored the Southern Mountains with up to 20 inches near Wolf Creek Pass and diminishing totals as you headed north. There was still some avalanche activity breaking near the ground, but most avalanches released in storm or wind-drifted snow. Avalanches continued to break on these mid-pack weak layers for some time to come. In the deeper snowpack areas forecasters were becoming less concerned about the deeper buried weak layers. In the thin snowpack areas these basal weak layers continued to plague us every time we got big storms. We finished December the same way as we started, with clear skies and cold temperatures.

The 2019-2020 season began with storms in the second week of October. The month closed with several more storms continuing on and off through the end of the month. Observers reported “excellent for October ” conditions. SNOTEL stations in the Northern and Central Mountains reported far more than typical amounts of precipitation, but “more than normal” in October still translated to rather thin snow cover with just a couple inches of snow-water equivalent on the ground. The CAIC recorded six small natural avalanches in the Northern and Central Mountains. A foot or less of snow fell in the Southern Mountains, enough to offer a glimpse of winter but not much snowy recreational opportunities.

First reported natural avalanche of the 2019-20 season. This soft slab avalanche released on a northeast-facing slope on Independence Pass around October 24 after receiving around a foot of snow in the previous week.

November began with almost three weeks of dry, mild weather. The snow that lasted through the dry spell on high-elevation north and east-facing slopes faceted into well developed depth hoar. This became the poor foundation upon which we would build the rest of the season’s snowpack. Thin crusts formed on sunny slopes that did not melt back to bare ground, and widespread surface hoar formed on the snowpack surface. Snowpack characteristics were similar statewide, other than more melting in the San Juan Mountains, and some isolated drifts of dense snow in addition to the depth hoar and thin crusts in the Northern Mountains.

Snowfall starting November 20 brought an end to the dry weather, and a corresponding uptick in avalanche activity across the state. Most avalanches ran on higher-elevation north and east-facing slopes and most broke into the depth hoar. With a shallow snowpack most avalanches were small, but the pattern was a sign of things to come. A series of storms would close out the month starting just prior to Thanksgiving. The snowpack failed this second test and we saw another avalanche cycle. We also started to see some variations across the regions.

This is an example of a shooting crack from the Aspen zone on November 22, 2019. Obvious signs of instability like these were widespread around the state when snowfall returned around November 20, ending our November dry spell.

In the Southern Mountains observers found shooting cracks, collapses, and a natural avalanche cycle that occurred the day after Thanksgiving. That prompted the first Avalanche Warning of the season on November 29. On November 30, two snowshoers triggered and were caught in an avalanche east of Red Mountain Pass.

This avalanche was remotely triggered from flat terrain on Red Mountain Pass on the last day of November. Avalanches like these gave us a good indication of how December would unfold when we got more loading events.

Snowfall from storms around Thanksgiving Day overloaded portions of the Central Mountains. The result was a cycle of small to large natural and human-triggered avalanches in the Gunnison and Aspen zones. The month ended with Considerable (Level 3 of 5) danger ratings and backcountry forecasts discussing the potential for people to trigger large avalanches near and above treeline on north through east aspects, especially around terrain features with wind-drifted snow.

In the Northern Mountains, a strong upslope storm developed just before Thanksgiving Day. A backcountry skier was caught and carried in a small avalanche while skinning uphill in Jones Pass on November 22. A backcountry skier was buried with just an arm above the snow near Searle Pass on November 28. A swift companion rescue prevented a tragic outcome. As snow continued to accumulate, avalanche size increased with a few large avalanches reported on November 29 and 30.

This small avalanche buried a person with only one arm sticking out of the snow on Thanksgiving Day. The other two people in the group quickly rescued the victim. The storms around Thanksgiving Day caused avalanche danger to rise and a corresponding increase in avalanche activity.

We ended the month on the way to better coverage, but with poor snowpack structure and weak layers ranging from depth hoar, to crust-facet combinations, to buried surface hoar. We were primed for more avalanche activity as soon as we got our next loading event.

As of January 31, we have documented 57 people caught in 42 separate avalanche events. Seven of the people have been critically (head under the snow) or fully buried, and two have died. 60% of the involvements this season occurred in January alone, including both fatalities.

Those are impressive and scary numbers.

How does this season compare to previous years? Before answering that question, there are several things to consider when we talk about avalanche accidents. We do know how many people avalanches kill. Fatal accidents are investigated and documented, which gives us confidence in the data. We do not know how many people are caught, injured, or buried in avalanches. We only know what people tell us. Many involvements go unreported, for reasons varying from embarrassment to people not knowing that we are collecting information or even that the CAIC exists. When there are well-publicized incidents, we tend to learn about other events. Thus, the number of people caught is an approximation, but we think it is indicative of patterns in avalanche involvements. The number of fatalities and incidents is relatively small, too. That means a single large event, like the 2013 accident in Sheep Creek, has a large impact on annual and multi-year trends.

So, caveats in mind, how does it look like 2018-19 will compare to previous years?

Comparing fatalities, 2018-19 looks similar to recent years. In four of the previous six winters, there were two or three fatalities by the end of January. The differences in total seasonal fatalities over recent winters tend to appear in February or April. Over the last few decades, most fatal avalanches occur in January, February, or March. Accidents in the spring separate typically tragic from exceptionally tragic seasons.

Comparing involvements paints a different picture. There were 32 people caught in avalanches in January 2019. That is nearly three times more people than in previous Januaries. Of the past 40 months with avalanche incidents, we only recorded more involvements in February 2013. The 56 cumulative involvements this year are far more than we recorded for all of 2017-18, 2015-16, and 2014-15. If we project similar rates to the end of the season, 2018-19 will be by far the most people involved in avalanche that we have recorded.

Only 6% of the people caught in avalanches in January died. That is slightly better than the long-term annual fatality rate of 8%. Several months, like February 2016 or April 2013, we documented relatively few involvements compared to fatalities and the fatality rate was over 20%. Those months highlight the potential uncertainty within monthly comparisons and the sensitivity of the small numbers in the dataset.

While these comparisons are interesting, there is not a single, easy explanation. There were 1113 avalanches record in January 2019, making it among the highest monthly totals. More avalanches were recorded in January 2017, though, with no fatalities that month. It is not simply a function of more avalanches. The type of avalanche may contribute. This winter, many of the avalanches ran on persistent weak layers while many in January 2017 ran on storm instabilities. More people are recreating in the backcountry, which could increase the number of interactions with avalanches. Those people may be reporting their involvements more often than in the past. We are learning about more close calls and successful companion rescues, possibly improved avalanche safety equipment. The line between avalanche tragedies and close calls may only be a matter of luck. A few events go slightly different–someone misses a tree, someone is caught further out on the slab–and our season could look very different.

We’d like to extend a Happy New Year greeting to all the Colorado backcountry enthusiasts. It’s been a great start to the snow year. The map below shows that a good portion of the state has near or well above average snow-water equivalent as we close out 2018. The Southern Mountains are still playing catch up, but a New Year’s storm is in the process of delivering some ample snowfall to the area. These are great conditions for winter recreation, but we are in the middle of the avalanche season and we want everyone to both have fun and stay safe.

Avalanche danger is ramping up with the New Year’s storm, and avalanche watches and warnings are in place for the San Juan Mountains. Although we likely won’t see enough snow for warnings in the Sangre de Cristo Mountains nor the Central Mountains, there will be enough of a new load to create dangerous avalanche conditions. Conditions are relatively safer in the Northern Mountains, but we still have stiff layers of snow resting on buried weak layers. You can still trigger a dangerous avalanche on steep wind-loaded slopes.

It’s not unusual for us to see avalanche accidents around the holidays and New Year. Over the last 10 seasons, we documented 11 incidents and accidents during the first week of the New Year. Three of these were fatal accidents. We don’t want 2019 to start out on a tragic note. Don’t let the excitement of new snow lead you into terrain not suitable for the changing conditions. Read the forecast, and pay attention to the travel advice. We want everyone to enjoy the great riding conditions and return home safely to friends and family.

In April the CAIC shifts from winter to spring operations. The exact date changes each year based on conditions. We make this change as the avalanche conditions become more uniform across the state and as the number of observations we receive decreases, making it difficult to assign danger ratings with confidence. Avalanche season doesn’t end in April, so instead of issuing forecasts for each backcountry zone we issue a single discussion of avalanche conditions for the whole state. As we approach this transition, here is what you can expect for the rest of the spring, summer, and fall.

We’ll continue to issue weather forecasts twice each day through the end of April. We typically issue a Statewide Avalanche forecast on Sunday, Wednesday, and Friday by 3pm. This year because of support from Cripple Creek Backcountry, The North Face, Bristlecone Mountain Sports, Ragged Mountain Sports, and Ute Mountaineer, we will be issuing zone forecasts for an additional week and then issuing the Statewide Avalanche forecast everyday through the end of April. In May we will issue the statewide forecast three times a week through Memorial Day. Our goal is to provide up-to-date and accurate avalanche information, so if conditions change we will update this product on any day it is warranted. We will also continue to issue Avalanche Watches, Avalanche Warnings, and Special Avalanche Statements any time the avalanche danger spikes or requires special attention. You can expect this through the summer and into the fall when we begin issuing regular products again on November 1.

by Nick Barlow

Colorado’s snowpack received much-needed help during January and February, including the first significant winter storms in the Southern Mountains. As we eye our next period of active weather ahead, we have an opportunity to place this year’s snowpack into its historical context.

Below, you’ll find recent data from the NRCS SNOTEL network. Data from these automated mountain weather stations shed light on the current condition of our snowpack. It’s been a difficult winter so far for snow lovers, but how bad is it really?

Winter storms since January 1st increased the statewide snow water equivalent (SWE) by about 19 percent vs. the historical median. The Southern Mountains realized the greatest gains during this period. The Wolf Creek Pass SNOTEL station measured 13.3 inches SWE since January 1st, which is 146% of the historical median for this period. However, the statewide seasonal numbers remain disappointing. The map above displays a general north-to-south gradient in snowpack deficit, with most stations in the Southern Mountains reporting less than 60 percent median SWE to date. Deficits are less in the Northern Mountains, where a few sites have SWE numbers near or even above the historical median. SNOTEL data in the Central Mountains varies significantly, with generally-better numbers observed east of Aspen and Crested Butte.

The chart above ranks this year’s SWE to date vs. all past years on record. The number indicates how many years had less accumulated SWE on the same date, so 1 indicates the driest year on record. The dataset is not standardized, as the period of record varies by station. Despite frequent winter storms since January 1st, some SNOTEL sites remain at their lowest SWE levels to date on record. Current ranks are generally better at selected sites in the Front Range, Vail & Summit County, and Sawatch zones. Notably, the current water year ranks seventh wettest at both the Buffalo Park (south of Rabbit Ears Pass) and Deadman Hill (west of Red Feather Lakes) SNOTEL stations. Hard to believe?

These products display snow water equivalent on the ground as of February 25th, but how does observed precipitation since November compare historically?

Accumulated snowfall since November 1st is at or above the 30-year average in portions of the Park Range, Northern Front Range, Sawatch, and San Juan mountains. Significant snowfall deficits exist west of Vail Pass, extending throughout the Aspen and Gunnison zones. Local variability certainly exists beyond the resolution of this product. Regardless, these numbers may appear surprising, unless we consider this winter’s pattern of storm frequency.

The current water year (October 1, 2017 – September 30, 2018) began with above-average mountain snowfall in portions of Colorado. Appreciable winter storms arrived during the beginning and middle portions of November, and also during the end of December and early January. Most recently, measured snowfall in February 2018 is above average for much of Colorado. The result is above-average snowfall this winter for some areas, but storms were too few and far between for the snowpack to develop accordingly. In other words, the storm snow sat idly for weeks at a time, while precious SWE sublimated or melted away. The redistribution of snow on the ground via frequent wind events could have also played a role.

On average, the statewide SNOTEL network realizes peak SWE numbers by April 9th. This means we have around one and half months remaining to make up ground on the historical numbers. Can we recover from the historically-dry fall and early winter period?

The chart above displays non-exceedance projections for our current water year. The heavy red line shows the observed statewide SWE as of February 24th, 2018. The thin colored lines (blue through red) indicate the range of possible futures. Blue-tinted lines indicate generally wetter scenarios, while red-tinted lines indicate drier scenarios. Here you can see the minimum, maximum, 10, 30, 50, 70, 90 percent non-exceedance scenarios. For example, the 90 percent exceedance line represents the boundary in the historical record in which 90 percent of the time any day’s SWE value will be below this value.

Only under the maximum and 90 percent statistical scenarios do we approach or exceed average statewide SWE before the spring runoff. While not impossible, both scenarios have a low probability of occurrence. The green line is the most-likely statistical outcome based on historical SNOTEL data. There is a 50 percent chance we end up either above or below any point on the green line. You can see we only have an outside chance of our snowpack recovering to long-term median values.

This chart breaks down peak seasonal SWE by month, displaying the current water year, past three water years, and 30-year median. With February nearly finished, Colorado’s snowpack is about 57 percent of the median peak. With our snowiest months already in the bank, median SWE in the mountains come April is an increasingly-unlikely scenario. Unlikely, but not impossible. Every water year has its own unique pattern, and yearly data rarely follows the historical curve. Intra-seasonal variability is common in Colorado, as our snowfall can arrive at different periods of the water year.

Unfortunately, low snowpack levels have consequences well beyond winter recreation. State commerce and tourism can suffer significantly during and directly following a dry winter. We also depend on a healthy snowpack for water supply and agriculture during the drier months. Finally, wildland fire danger can increase significantly following dry winters.

We all want more powder to play in, but there is much more at stake in the crucial weeks ahead. Winter snowfall is the lifeblood for continental climates like ours.

By Brian Lazar and Blase Reardon

Fall snow in the mountains – white snow bannered between blue sky and golden aspens. What to make of it? Maybe you hear people bemoaning it as a sign that their biking, climbing, fishing or gardening seasons are coming to an end. Maybe you hear others extolling it as the promise of a powder-filled winter ahead. Maybe you hear grizzled veterans grumbling that it’s too early, and we’re on the road to developing our first unpredictable and potentially dangerous weak layer. Let’s consider that last response, and outline some tips on how to deal with that issue.

The fall snow is shallow. That’s its most significant feature. It’s susceptible to melting or weakening, and both processes can have long-term effects on snowpack development and avalanche conditions as the winter progresses. The outcomes depend on future weather.

Melting:
A combination of radiation and heat can melt the early season snow. Sunny slopes are the first to melt off. If temperatures are warm enough, even shady slopes can melt back to bare ground. A prolonged spell of sunny, warm weather will leave slopes (especially those receiving direct sun) bare of snow, or dotted with thin, discontinuous snow patches. This would a good thing from an avalanche perspective. It would mean subsequent snowfall will be falling on mostly bare ground, without preserving any weak layers at the bottom of the snowpack.

Weakening:
High-elevation shaded slopes aren’t as impacted by radiation and often don’t warm enough to melt snow. On these slopes the thin snow cover lingers. Temperature gradients – in this case the difference in temperature between the ground and the snow surface – can be very high. The temperature near the ground hovers near freezing. At the snow surface, it’s generally colder; sometimes much colder. High temperature gradients promote faceting of the snow grains. With time, this thin layer of early season snow can change into a weak layer of large-grained facets; a layer that collapses when sufficiently loaded. That weak layer will be at the base of any snowpack that accumulates above it. That’s a bad thing.

Some of both:
If the radiation and heat aren’t sustained, they might leave just a crust on the surface of a shallow snowpack. Crusts near the base of the snowpack are notorious for producing thin layers of facets that can persist for long periods. That means ongoing Persistent Slab avalanche problems, if they’re buried. Some of our worst years for Deep Persistent Slab avalanches occurred when early season snow first faceted, and then melted just enough to cap the basal facets (depth hoar) with a thin crust. Neither of these scenarios is great for our avalanche future.

So, what’s a snow-lover to do at this point? Monitor the weather and snowpack from here on out. Below are some things to watch:

• Snowline elevation: Put a number on the lowest elevation at which you see snow. Find some markers on a slope you can view regularly, compare them to a topographic map, and check the snowline against those markers. Once snow starts accumulating, you’ll know the elevation above which you need to factor basal facets into your assessments. Or conversely, the elevation below which you don’t.
• Aspects: Be very conscious of the aspect the slopes where you do and don’t see snow. Use an online mapping tool or a compass to verify your impressions. Being able to differentiate slopes by aspect will again help you include basal facets in your assessments when they’re likely to be present. And deemphasize them when they’re not.
• Snow surface: You’ll need firsthand info to determine whether a crust/ facet combination is developing. That can be opportunistic – checking for it if you are up high or asking people who have been – or planned.

Images of your favorite backcountry areas can serve as great references later. The most useful images are those taken just before the season’s snow accumulates, when you can see the distribution of any persistent old snow. Because it’s hard to time that, take images whenever good weather allows.

These practices are focused on determining the distribution of potential weak layers. They don’t tell us much about the actual layers. That we can learn once winter hits in earnest. For now, think “where.”

At this point, we’re hoping for one of a couple scenarios:

1. The snow on the ground now melts away back to bare ground. That way we could start from scratch when we’re more likely to get consistent snowfall.
2. Bury this early season snow with more snow; lots of it and fast! Once we have snow on the ground that is likely to stick around, the more quickly and deeper we can accumulate more snow, the better in the long run. We’re hoping for a snowpack deep enough that temperature gradients aren’t high enough to promote faceting/weakening of the snow on the ground.

Many places that picked up more than 1 or 2 feet of snow in early October now have enough snow to make scenario 1 unlikely. Scenario 2 doesn’t look great either with the mid-range forecasts. That’s leaves up hoping we don’t cap our currently faceting snowpack with a crust. It’s not the best way to start, but it’s not the worst (yet).

by Brian Lazar and Ethan Greene

Santa delivered a lot of snow to Colorado in the past two weeks, just in time for Christmas. Have we been naughty or nice? Well riding conditions have been fabulous, but there have been some impressive avalanches.

The last storm brought significant snowfall and avalanche activity, but since then the snowpack has been getting stronger and we’ve seen fewer avalanches and less cracking and collapsing.  Paradoxically, this does not mean things are necessarily safer for the backcountry traveler. The likelihood of triggering an avalanche is decreasing, but the size and consequences of avalanches that do release are steadily increasing.  This trend has prompted discussions amongst our forecasters about whether or not we are moving into a new risk paradigm, and perhaps, a new avalanche problem: Deep Persistent Slab (DPS) avalanches.

DPS avalanches have many characteristics in common with Persistent Slab (PS) avalanches. Both break on persistent weak layers. You can trigger both remotely and from low-angle slopes. Both of these types of avalanches can fail in surprising ways, breaking across and around terrain features that would contain a Storm or Wind Slab avalanche. PS and DPS avalanches have a lot in common, but there are some very important differences that affect how we avoid them and manage our own personal risk.

DPS avalanches are low probability and high consequence events. The likelihood of triggering a PS avalanche and the size of that avalanche can vary over a wide range. DPS avalanches are a specific creature, very large in size and hard to trigger.  We look for three things before we add it to our list of Avalanche Problems. Those three things are:

• Avalanches will be  stubborn to trigger,  Unlikely or Possible on the Likelihood scale
• Avalanches will be destructive,  D3 or larger
• Avalanches will break on deeply buried or basal weak layers

These criteria capture the low-probability/ high-consequence nature of DPS avalanches.  A low Likelihood means there will be very few or no natural avalanches, human-triggered avalanches will be unlikely, and large explosive and cornice triggers will only produce some results (ADFAR2).  A D3 (Very Large) avalanche could bury and destroy a car, damage a truck, destroy a wood frame house, or break a few trees. When the likelihood slider drops towards “Unlikely” and the size slider climbs to “Very Large or Historic”, we have a DPS avalanche problem (see image below).

DPS avalanches are especially scary because most people don’t have much experience dealing with them.  It is hard to gain experience dealing with these beasts because we don’t see DPS avalanche cycles that often. In a typical year we could see over twenty cycles of Storm, Wind, and Persistent Slab avalanches, but we may only see one DPS avalanche cycle in five years.  You could navigate through two Storm Slab avalanche cycles in a week of touring, but it could take you ten years to gain the same amount of experience with DPS avalanches. These avalanches are also very large and extremely dangerous. Most people that get caught in one get killed.  This makes it very difficult to learn from a close call. Your first encounter with a DPS avalanche could very well be your last.

Over the last 15 years, almost all avalanche accidents in Colorado where more than one person died were the result of a DPS avalanche. In two seasons with pronounced DPS avalanche cycles (2008-09 and 2012-13), DPS avalanches accounted for more than 60% of the avalanche fatalities.  In the figure below (covering two seasons: 2012-13 and 2013-14) you can see that avalanches involving persistent weak layers are particularly dangerous. DPS avalanches only accounted for 5% of the observed avalanches, but caused 42% of the fatalities.  Sure sounds like low-probability/high-consequence, doesn’t it?  You can read the whole study here.

In a year with DPS avalanches we can describe the forecast zones where they could happen and the aspect and elevation of the slopes that are most likely to produce one. This is the good news. The bad news is that if you have ten of those slopes, it is really hard to predict which one will produce a DPS avalanche. This is the low probability part. Remember the other half of the description is high consequence. Because DPS avalanches are so dangerous, the only safe way to manage your risk is by avoiding those suspect slopes. On a bad year, you might have to avoid those slopes for the rest of the season. This can be hard to do because people will test suspect slopes, and most will get away with it (they are low-probability events). And due to the nature of a DPS avalanche problem the danger is almost always MODERATE (Level 2) when this is our main avalanche problem, because these avalanches are hard to trigger. That combination -people testing slopes without immediate consequences and a MODERATE (Level 2) rating – doesn’t scream “dangerous” the way an avalanche warning does.

So where are we this year?  In some places we can produce D3 avalanches, as demonstrated by the mid-December avalanche cycle.  Between December 14 and 21, multiple D3 avalanches released in the Aspen, Gunnison, North San Juan, and Front Range zones. This includes both natural and human-triggered slides.  Around half of these avalanches ran naturally during and shortly after the storm cycle. So while we met the size criteria, we weren’t at the point where we called these avalanches stubborn to trigger. Instead, we had Likely to Very Likely, and Large to Very Large PS avalanche problems. This resulted in avalanche warnings and HIGH (Level 4) danger.

The likelihood of triggering PS avalanches in these areas has since decreased, but some notable D3 avalanches released post storm.  A narrow escape near Crested Butte, a very large avalanche triggered by a snowcat near Loveland Pass, and explosive triggered slides north of Berthoud Pass, and very large avalanche with an unknown trigger near Cameron Pass have us talking about if a potential DPS problem is in our future.

It is getting harder to trigger an avalanche that breaks into the weak snow near the ground in most of the forecast zones. So the Likelihood of triggering a Persistent Slab avalanche in decreasing. We have seen Very Large (D3) avalanches in the Aspen, Gunnison, North San Juan, and Front Range zones.  Most of these zones have a deep enough snowpack to produce more Very Large (D3) avalanches.  The Sawatch and Vail/Summit zones picked up less snow during the mid-December storms. Most of the avalanches in these zones have been large enough to kill you (D2), but not large enough to destroy a vehicle or timber structure (D3).We have a basal weak layer, the avalanches are getting harder to trigger, and in some zones they getting quite large. Although we have not started to warn people about DPS avalanches, some of the PS avalanches are getting larger and harder to trigger. The weather over the next couple of weeks will determine if we are just going through a scary period, or if we’ll move into a DPS cycle that lasts the rest of the season. For now, remember that we’ve seen some tricky conditions over the last few weeks and there is no indication they are over. Please read the forecast before you go out and keep in mind that this kind of Moderate (Level 2) danger includes some pretty big avalanches.

Stay safe out there and enjoy the snow!  Happy New Year!

Click here to learn more about Avalanche Problems from the USFS National Avalanche Center.

By Nick Barlow

One of the most useful resources provided on the CAIC webpage is the weather stations page (Observations > Weather Stations). Here you will find a table of hourly and archived observations from a large network of weather stations throughout Colorado, sorted by forecast zone and elevation.

The several highlighted columns report different quantities of precipitation. For SNOTEL stations, up to seven different readings are given. Below is a description of these readings, the instruments that take them, and how the data can be useful for backcountry users.

Snow Water Equivalent (SWE)

SWE is the total amount of water contained in a fixed sample of snow. More simply, it is the resulting depth of water if the entire sample melted. In this context, “sample” could mean the entire seasonal snowpack (SWE), or just new snowfall over the past 24-hours from a single storm (SWE24). Seasonal SWE is particularly useful for long-term hydrological applications, such as forecasting water supply or seasonal runoff. For example, water managers use the data to determine how much water is stored in the mountain snowpack for the warmer months ahead. This is the primary function of the SNOTEL network, and the strategic placement of stations in important water basins throughout the United States. Yet SWE is also relevant for backcountry users.

The density of water varies only slightly with temperature. By contrast, snow density varies significantly from storm to storm. The SWE calculation is a way of standardizing snowfall for use in further applications. When we think about loading weak layers in the snowpack, calculating SWE can be of great value. The data can reveal the load added to the snowpack from an individual storm.  By comparing SWE to snow depth, we can also discern whether the storm snow was dense and heavy vs. light and fluffy.

At SNOTEL stations, SWE is measured using snow pillows: large 3-meter x 3-meter bladders (steel and rubber) installed on the ground and filled with a volume of antifreeze. As snow accumulates on top of the pillow throughout the winter, instruments measure the increasing hydrostatic pressure upon the liquid. With that, the mass of the overlying snow is calculated.  Knowing the density of water allows us to calculate SWE. A snow depth measurement allows us to calculate snow density.

Measuring Snow Depth

Snow depth is perhaps the easiest quantity to measure, simply by using a ruler or avalanche probe. It is more complicated at remote weather stations with the automated measurement and logging of data.

At SNOTEL stations, an ultrasonic depth sensor mounted above the snow pillow measures the snow depth. The sensor sends a signal downward towards the ground and measures how long it takes the signal to bounce off the snow surface and return to the sensor. Knowing how fast the signal travels, a properly-calibrated sensor will give an accurate reading of snow depth.  On the weather station page, there is a field for changes in depth over a 24-hour period (Sno24), in addition to the total depth of the snowpack (SnoHt).

The ultrasonic sensor is also useful for backcountry users. Most simply, it is the only tool at a SNOTEL station that can tell you how much new powder you’ll find on any given day. However, you can glean more, and more important information from a SNOTEL site.

For one, the total depth of the snowpack can be particularly useful. A shallow snowpack can promote changes in snow structure, and create persistent weak layers. This is important information to gather before traveling into the backcountry. On a shorter time-scale, the amount the snow depth increases in a single storm is a good estimate of how much snow is available for wind transport. We can also estimate the depth of new Storm Slab or Wind Slab avalanches, and at what depth we might find the old/new snow interface in our snow pits.

Measuring Liquid Precipitation

SNOTEL stations are equipped with a precipitation gauge to measure liquid for the entire water-year. During the warmer months, rain simply falls into the gauge. The gauge then measures and logs the data automatically. Snow also falls into the same gauge during the winter months. However, sub-freezing temperatures would make any kind of liquid measurement essentially impossible. To combat this effect, SNOTEL precipitation gauges are “charged” with a volume of propylene glycol, melting the snow on contact as it falls into the gauge. The gauges also contain mineral oil, designed to sit on top of the collected liquid and prevent evaporation over time. On the weather station page, data is in 1-hour (Pcp1), 24-hour (Pcp24), and since-midnight (PcpAc) format.

For backcountry users, liquid precipitation data can also be useful. Ideally, data from this gauge would match the calculated SWE data from the snow pillow and ultrasonic sensor. This is not always the case. It’s important to recognize the differences and primary functions of each piece of equipment. Data from the liquid gauge is used for seasonal purposes. The gauge keeps measuring precipitation long after the snow melts away from the snow pillow.

However, the data can be used in conjunction with the SWE and snow depth in order to provide a more well-rounded answer to what is going at the station. An example would be for rain-on-snow events.

Snow pillows may not always capture added SWE from rainfall, as some of the liquid may channel away from the pillow. In this case, the liquid gauge is the only piece of equipment that could tell us if rain-on-snow has occurred. A simultaneous temperature reading from the SNOTEL could also reinforce our suspicions.  

Takeaway

Remember that automated SNOTEL stations exist in remote mountain locations. The stations use three different pieces of equipment to measure precipitation, and each piece has its own unique purpose for being there. Like any equipment, the gauges are prone to both random and systematic errors, and the data may not always be trustworthy.

A variety of issues can (and do) arise at SNOTEL stations. For this reason, they require continued maintenance and quality control of the data they output. This can be exceptionally difficult during the winter months, as access to many of the stations is difficult.

As backcountry users, we should analyze each piece of data individually before forming a conclusion about what has transpired. Compare the different forms of output (SWE, depth, melted liquid) and attempt to read between the lines.

Also, recognize the data is from a single point, and may not be representative of the entire area in which you’ll be traveling. Of all meteorological surface measurements, precipitation is by far the most spatially variable. You will likely find inconsistent snowfall results within different elevation bands and aspects as well. Study the data from other near-by stations; learn which stations typically receive more or less snowfall than others.

Most of all, be thankful the SNOTEL network exists. It is a wonderful tool to have at our disposal. These stations shed light into the dark and cold, providing us with vital information at just a mouse-click away.

As of March 1, avalanches have killed 23 people in the United States this winter. This is the second largest number of cumulative fatalities through February since the winter of 2000-01. Unlike January 2016, the six avalanche deaths in February 2016 were typical for the month (median 6). Typically, about 60% of avalanche fatalities for the winter have occurred by March 1. Projecting forward, 2015-16 could be one of the worst winters for avalanche deaths in recent years. This is a rough estimate, and how the snowpack evolves over the next few months will determine the number of serious avalanche accidents.

The chart below shows cumulative fatalities by month for avalanche years 2001 through 2015 in gray. Median, first, and third quartiles are shown in blue. The cumulative fatalities for 2016 are in red. Mouse over the chart for monthly values.

[Updated February 3, 2016] As of February 1, there have been sixteen avalanche accidents resulting in fifteen fatalities across the US this winter.  Thirteen of the deaths occurred in January 2016,  with ten of them occurring in the span of nine days between January 16 and 24.  Two of the fatalities occurred in Colorado. This is a very large number of fatal accidents in a relatively short period. We can look at previous winters to see how unusual this cluster of accidents is. Unfortunately, the answer is “unusually bad.”

Since 1950, January is the month with the most avalanche fatalities. The 12 fatalities in a single month is the largest number of fatalities in January since 2008, when 19 people died in avalanches. The winter of 2007-08 was one of the worst seasons for avalanche fatalities in the last 65 years.

In the last 15 winters, February has taken a slight lead, with 22% of the total fatalities compared to 21% in January. During that period there have been between 2 and 6 fatalities in January. In addition to January 2008, only February 2014 (12 fatalities) and February 2012 (13 fatalities) had similar numbers of avalanche deaths within a month. The 2011-12 and 2013-14 seasons were also among the worst seasons for avalanche deaths in the last 65 years.

In the United States, about 70% of fatal avalanche accidents occur within four days of a prior accident (Logan and Witmer 2012). These clusters results in long accident-free periods, then a period with several accidents, followed by another long accident-free period. Within a cluster, it can feel like an unusually high number of accidents.

The statistical analysis does not reduce the pain and loss with each fatality. Each one leaves a hole in the heart of the victim’s family, friends, and community. The analysis does help us place current tragedies within a longer context. There have been an unusual number of accidents recently. This may be an indication of how accident patterns will evolve over the rest of the winter.

As I touched on before, language that minimizes close calls can reinforce overconfidence and an illusion of skill. A close call doesn’t count or isn’t that serious, because it’s an exception, because nothing really happened. It must be our abilities that made the difference. And with these abilities, we can take more chances.

I’ve wondered how to break that cycle. Recently, I heard how it happened for a friend and occasional ski partner. We were talking while skinning on a mild day. He’s had at least three close calls, two of them involving large avalanches. He’s never seemed to shrug off the incidents, and he takes avalanche safety seriously. But still, the hits just keep on coming. Enough so that he and his frequent partners earned the nickname “The Wrecking Crew.” The most recent involved a small avalanche earlier this season.

I was surprised to hear that he’d hardly skied in the backcountry since then. I figured it was just conditions. “No,” he said, “it was like a switch got flipped. Suddenly it just seemed so risky.”

The defining incident had happened early one morning, on what was supposed to be a casual one-n-done with some of the Wrecking Crew. The group had an inconclusive discussion about a line down the bowl, with at least one member of the group arguing that they stay away from the bed surface of an older slide. It had been reloaded with new snow and a few days earlier someone had triggered a second, smaller slide that released the new snow on the other side of the bowl. My friend watched the first skier nonetheless turn into the old bed surface and trigger a small slide that briefly knocked him off his feet. He recovered and escaped out the side.

Several things made this incident feel different for my friend. The skier who triggered the slide was recovering from knee surgery. My friend said that while he watched the skier struggle with the debris, “I kept thinking about his knee and how it would suck for him to get hurt again.”

This incident was also more of a surprise, unlike the previous ones, when he knew he was pushing the line and far more prepared for something to go wrong. “It was supposed to be a casual day. We weren’t really going to be exposed to much danger. The terrain and the danger were moderate. Yet something still happened. I realized it could happen anytime.”

The big thing, though, was a conversation with one of the others in the group when they arrived back home. “We looked at each other at about the same time and said, ‘That was not ok, was it?’ And it was like waking up after one too many frat parties.”

My friend and I had a good tour together that day. I didn’t ask him if skiing in avalanche terrain felt different this time. I don’t know that there’s a recipe for replicating his come-to-Buddha moment. I do see some elements that seem common to people who aren’t overconfident: a visceral sense of the consequences of a slide, an awareness that avalanches are unpredictable and ultimately unmanageable, and lastly, a willingness to listen to friends who don’t write off close calls.

blase reardon

A recent conversation illuminated how people can perceive the risk involved in their decisions and actions very differently than others do.  The subject was driving skills, but it could just as well have been backcountry travel. I’ll paraphrase the conversation, and I have slightly altered and exaggerated some details in the interest of making a point.

The conversation was prompted by a comment that a friend wouldn’t have to speed on her morning commute if she left home 15 minutes earlier. She offered a spirited defense of her driving. “Speed limits are suggestions. There’s no need to drive less than 5 mph over the speed limit if there’s no inclement weather. People that drive less than the speed limit are dangerous.”

Her audience wasn’t buying it, so she escalated her defense. “I’m a good driver. I’ve only had one wreck. And that was because of black ice.” The car incurred damages of $10000, but she only paid the deductible, so it didn’t count as a serious accident in her mind. “And two tickets.”, she added.

It came out that she’d only learned to drive in 2009. A listener pointed out that three incidents in five years was a pretty high rate of getting into trouble. She argued that the second ticket shouldn’t count, as she was speeding to pass a semi. “Don’t you think that driving next to a semi is unsafe?” she asked the trooper. She threw in that it was her birthday, but he gave her a ticket anyway. “I couldn’t flirt my way out of it, like I had other times.” The “other times” were three more traffic stops in which she hadn’t gotten a ticket. That meant a rate of more than one incident for each year of driving.

“That’s not bad. I’m a good driver.” Someone noted that some people go their whole lives without a ticket or an accident. “They’re probably the people going 10 mph below the speed limit and making it dangerous for everyone else.”

She then told a story about driving 100 mph on I-70 in a borrowed Audi because the car is designed to hold the road better at high speeds. She offered to drive anyone home. There were no takers.

My friend seemed to feel that deft car-handling skills equate to safety. Many of her defenses sound familiar; I’ve heard similar sentiments in conversations about skiing and riding in the backcountry. Somehow, the unintentionally-triggered slides and the near misses don’t count because of some circumstance specific to that incident. They become confirmation of skills rather than lessons. An avalanche flank 15 feet from your track isn’t a close call; it’s proof you knew how to pick your line. Flawed conclusions like that are easy to draw in a wicked environment like the backcountry, where irregular feedback promotes learning the wrong lessons from our experiences, and encourages an illusion of skill.

I don’t know whether my friend drives as recklessly as she sounded in that conversation. Nor the balance of over-confidence and expertise of anyone I meet in the backcountry. I do know I aim to second-guess my own claims to expertise and skill. I try to imagine what they’d sound like out of context, after an accident perhaps. Andre Roch ‘s famous quote, purportedly made after one of his own near-misses, applies here: “The avalanche doesn’t know that you are an expert.” It’s the quality of situation-specific decisions that matters. And every close call counts. The backcountry doesn’t offer a good-driver discount.

blase reardon

Blase Reardon

On January 17th, 2014, a pair of riders triggered a large avalanche on a steep, near-treeline slope in the backcountry behind Snowmass Ski Resort. The slope had previously been nicknamed “Mr. Magoo’s” after a ski patroller who sometimes acted like the near-sighted cartoon character. The riders escaped unhurt, despite an ugly terrain trap below. An hour later, the resort’s snow safety director watched a solo skier turn down the same slope and trigger a second slide adjacent to the first. He met the solo skier as he returned to the resort and asked him whether he’d seen the first slide—or the larger natural avalanche just up the drainage at the same aspect and elevation. The solo skier replied, “It’s okay; I have skied Silverton and I skied the path a couple of years ago.”

The slope where the January 17th incidents occurred is steeper than 35 degrees and faces southeast. On that day, it was blanketed with a foot-thick slab formed by a recent storm and subsequent cross-loading; the slab sat on a thin, persistent weak layer. It was a slope that closely fit a pattern of recent avalanche activity and that was highlighted in the CAIC forecast as the kind of slope where people were most likely to trigger slides. With the danger rated as Considerable, skiing that slope on that day was a risky proposition, especially alone and with a fresh slide visible.

The solo skier didn’t answer the question posed to him – did he see the other slide and, implicitly, was he concerned about avalanche danger on the slope? Indeed, he seemed to answer a different question altogether, one centered on skiing rather than avalanche conditions. Perhaps standing at the top of Mr. Magoo’s he asked himself, “Can I ski a slope like this?” And his answer seems to have been “Yes, because I’ve skied slopes this steep before. I’ve even skied this slope before.”

According to Nobel-prize winner Daniel Kahneman, substitution like this is a nearly automatic cognitive response to complex, irregular environments. Our brains produce what Kahneman calls “off-the-shelf answers” to difficult problems by answering simpler, more familiar questions. It’s a sub-conscious process, and it provides solutions that leave us feeling very confident in our assessments and choices. Assessing the risk of triggering a slide on a steep slope covered with new snow is a complex task, fraught with uncertainty. Faced with that, our brains quickly default to questions with simpler answers, like “Can I ski this slope without falling?” or “Will the skiing be as good as it looks?”

Marketing provides numerous everyday examples of this pernicious tendency. When faced with a question like “Is this the best pair of skis for me to buy?” we often answer a question more like “Do I like this brand of skis?” or “Do I like the graphics?” In situations like these, substitution often provides adequate answers, because the alternatives aren’t that different and the consequences of not answering the initial question aren’t severe. And substitution has the advantages of saving us mental energy and time. Once we’ve substituted a simple, seemingly coherent answer to a complex question, we can confidently summon numerous arguments supporting our choice without recognizing the substitution.

That leads us back to Mr. Magoo, the cartoon character referenced in the slope’s nickname. Mr. Magoo stubbornly refuses to recognize his near-sightedness. He doesn’t have to, because situations always work out for him. Magoo mistakes an airport for a movie theater, takes a seat on a departing plane—”It’s like I can feel the plane taking off!”—wanders around on the wings, unknowingly leads the police to a bank robber, and when the plane lands, tells the flight attendant he really enjoyed the film. The tension in the Mr. Magoo cartoons derives from seeing how lucky the character can get yet be oblivious to the dangers he’s facing, thanks to his near-sightedness . They’re funny because we know his luck will never run out.

We can all be Mr. Magoos in the backcountry. When nothing bad happens, it’s easy to finish a day of skiing or riding in avalanche terrain feeling confident we made good choices. So it’s easy to take the wrong lessons from our experiences. We’re sure we really liked the movie, unaware of how close we came to falling off the wing. The three riders involved on the slides on January 17th might easily conclude that they judged conditions correctly. More correctly even than the forecast, which called slopes like Magoo’s dangerous. None of them were hurt. The answer of “Yes, I can ski this” seemed to work, so the solo skier might be more likely to rely on it the next time he’s faced with a slope where the stability is questionable.

The winter backcountry is no cartoon, however. Substituting an easy question for the relevant one can kill our friends, our loved ones, or us. Our luck can run out. Or we may not get lucky at all. It’s what Kahneman and others have termed a “wicked environment”—an environment in which a lack of regular, reliable feedback allows us to develop habits and patterns based on faulty correlations, or luck.

So, what’s the alternative, given our brain’s hardwired proclivity for substitution and the wicked nature of the backcountry? How do we keep from being Mr. Magoo?

In previous section of this article, I noted that the winter backcountry is an instance of what Nobel-Prize winning researcher Daniel Kahneman and others describe as a “wicked environment” for developing expertise. In part, that’s because expertise in the backcountry is a collection of skills. We have to master the individual elements—technical skiing and riding skills, route-finding, and stability assessment among them—while simultaneously learning which items in the set to prioritize and apply in a given situation. It’s also because in the winter backcountry, we don’t get much immediate, consistent feedback on our decisions and actions. We rarely know how close we are to triggering a slope, so it’s easy to develop habits and patterns based on faulty correlations, or luck.

A real-world example of the rarity of immediate feedback in avalanche terrain surfaced a few years ago, in a video posted on YouTube that’s since been pulled. It showed a skier finishing a run on Puckerface, a steep slope near Jackson Hole Mountain Resort. The soundtrack includes lots of whooping. Then a title card appears, reading “Second Run. 10 minutes later.” A snowboarder starts down the same face, and makes a hard first turn. The entire slope fractures several feet deep, and slides. The snowboarder claws into the bed surface and stops. The camera shakes and jerks, accompanied by lots of cursing. The snowboarder walks away on the ridge. The video shows the slide a second time, in slow motion.

Let’s put ourselves in the boots of the first rider on Puckerface on January 2, 2012. We choose to ride the  slope for some reason—maybe a well-considered assessment of stability, maybe by substituting a question that’s easier to answer, like whether there’s enough sun on the face for good video. When it doesn’t slide, we conclude our rationale was correct. Given enough similar experiences, we could start to feel very confident in our skills. But the slide triggered by the second rider reveals a more accurate conclusion: we got lucky. And instead of developing skills, we might just be getting lucky, a lot.

The image above also shows Puckerface on an early-winter day, this time nearly two years later, on Dec. 26, 2013. On this day, a rider wasn’t so fortunate; he was killed in the slide visible in the image. That’s the potential penalty for substitution, inadvertently relying on luck, or just plain making a mistake. Each day in avalanche terrain, each run or route we chose, is unique and novel; we have incomplete or ambiguous data, we get one chance, and the cost for choosing badly can be fatal.

An alternative to relying on luck is expert intuition—distinguishing familiar cues in a new situation and choosing an appropriate response. As Kahneman notes, “Expert intuition strikes us as magical, but it is not…[It] is nothing more and nothing less than recognition.” It’s Mr. Magoo with eyeglasses, a prescription that lets him recognize an airplane instead of confusing it for a movie theater. In his classic essay “The Ascending Spiral”, pioneering snow scientist Ed LaChapelle echoes that point; intuition “is not some sort of extra-sensory perception.” He describes it as a “lifetime accumulation” of observations about snow, avalanches and weather. That doesn’t just happen, because the backcountry is a wicked environment. We help develop it by adopting simple habits that, over time, make the backcountry environment more regular and expand the base of stored cues necessary for expert recognition.

Below are examples of practices  that can improve the quality of our observations, our communication, and the feedback for our decisions.

It’s all about the up: Most—at least two thirds—of our time in the backcountry is spent going up. It’s our best opportunity for observing and communicating. It’s also when most miscommunications and mistakes occur. Set a low-angle, meanderthal skin track that takes advantage of the terrain to investigate different aspects and slope angles, and that allows relaxed discussions of your observations without having to stop. Steep skin tracks make it hard to see much beyond your ski tips, and even if you do notice something important, it’s hard to communicate it when you’re anaerobic. If you’re breaking trail and can’t hear the group behind you talking, your track is too steep for easy observations and communication.

Give it a rest: Take breaks at decision points. Fiddling with your clothes or gear randomly just slows you down yet provides little information about snow conditions or route choices. Stopping to drink, eat and layer up when you’re faced with a decision is productive; it allows you to look around when you’re comfortable and talk about what you see. More often than not, you’ll pick up nuances in the terrain that you didn’t see while moving and out of breath—as will your partners. And you’ll make better decisions when your brain isn’t starved for oxygen or nutrition. Pace your group so you’re moving steadily and don’t feel rushed when you stop at decision points.
You are not the Captain now: Encourage feedback within your group. You’re looking for ideas that can save your ass, not aiming for agreement. It helps to rely on questions rather than declarations. “Does that side of the slope look wind-loaded?” instead of “Most of the slope isn’t wind-loaded.” Listen for contrarian opinions rather than trying to silence a squeaky wheel. Acknowledge that anyone in the group has veto power.

Write it down: Keep a field notebook or submit observations to your local avalanche center after each backcountry trip. It’s a sure way to notice and remember details about snow and weather conditions.. Summarizing them for a field report forces you to make sense of what you observed, to sort what’s most important from what’s irrelevant. And it gives you something besides dim memories when you’re checking impressions of past events.
Debrief: When we talk about a day in the backcountry immediately afterwards, we often focus on the highlights—the great run, the funny fall, the beautiful light or snow. You provide otherwise unavailable feedback on your decisions by including an opportunity to talk about how you did things and whether those actions put you at risk. Guides often do this formally, in afternoon meetings in which they can identify when they were most at risk during the day. A friend’s more informal approach, is to ask, “Well, did we get it done, or did we get away with it?” Find a way to expand your end-of-day conversation to more than high fives. If something nags at you a day or a week later, talk with your partners so everyone understands and learns from the experience.

Find a mentor: Years ago, I spent a day traversing a high peak in the Wasatch with a mentor when the avalanche danger was high.  It was a lesson in micro-route-finding. Near the end of the day, when it seemed we’d mostly passed the hazards, I took a few extra turns on a small slope I now recognize as a terrain trap. I looked up to see my mentor giving me a look that said, “That. Was. Dumb.” That look still floats into my consciousness when I encounter similar slopes. Though the look clearly communicated stupidity of my move, it was much more forgiving feedback than triggering the slope. Or another like it, because without that mentorship I might have gone much longer without learning to take small slopes seriously. You learn from (and with) a mentor in an iterative process, the goal of which is your becoming equally skilled and knowledgeable, perhaps more so, than your mentor. This relationship is different than that with a guide, who may pass on some useful tips but who is a leader.

Others with extensive expertise in the backcountry can offer up other practices like these, which may work better for them or better period. The point is less the specific habits than making an effort to maximize the quality of our decisions and the feedback we get for them, so we have the best chances of seeing our Mr. Magoo-like close calls and learning from them, without the too-painful learning that comes if our luck runs out.  Time in the backcountry with that kind of reflection is what leads to the lifetime of accumulation and instant recognition that Kahneman and LaChapelle identify as expertise.

2 years ago I was traveling in India with Water For People. I was lucky enough to spend time with my amazing colleagues, who really opened my eyes to the importance of ownership, co-investment, and public-private partnerships. My colleague from across the world, Satya, and I walked through one of the poorest communities I have ever seen, and we discussed why this community was flourishing. Water For People had catalyzed the relationship between the State government and the people of this community. Water was flowing, and a public-private partnership had been developed to ensure that it continued to flow in the future. The community invested in their water system and the sustainability of it. They invested in something they wanted and saw a need for.

6 years ago, I started fundraising for the Colorado Avalanche Information Center. I read about a chain of events that was going to cost the center $25k in funding. My initial thoughts about what was happening were negative and also incredibly unproductive. However, my second thoughts, and a discussion with a friend, made me realize that I can help. This is our avalanche center, and we can’t afford to see it lose any funding or decrease the backcountry forecast operations in any manner. This one article 6 years ago is what started the CAIC Benefit Bash, an event that now raises $100,000 annually to go toward avalanche forecasting and education throughout the State of Colorado. Then I was a volunteer. Today, I am the Executive Director of the Friends of CAIC and asking you to help us reach our fundraising campaign goal of $150,000.

The Colorado Avalanche Information Center’s Backcountry Avalanche Forecasting program is small but mighty. The program has grown over the past 10 years but with only 6 forecasters operating in 10 zones, we still have a long way to go to provide the service needed by the backcountry community. Colorado is a very big place and there are more and more people enjoying the State’s spectacular winter backcountry each year. Our goal is to provide the best avalanche center in the country. To achieve this goal we need everyone’s support. The State of Colorado is incredibly supportive and has increased the CAIC’s funding this last legislative session. But to really expand, we need every user involved as well. This partnership is the best way we can grow the CAIC’s backcountry forecast program, and I am personally asking you to support avalanche forecasting and education throughout the State of Colorado.

This is your avalanche center and to ensure we continue to have the best avalanche center in the country we need your help. These public-private partnerships are solving the world’s toughest problems. We have developed the same model to create the best avalanche forecast center in the United States.

Join us by donating here: http://www.crowdrise.com/StayInformedStayAlive

Aaron Carlson
Executive Director
Friends of CAIC

We tend to think about hazard on a spectrum of both likelihood and consequences. The likelihood that a given incident will occur can range from low to high. If an incident does occur the resulting consequences could range from low to high. An example of a high likelihood low consequence event is when you forget to put on sunscreen and you get a sunburn. Similar to likelihood is the frequency at which an event might occur. A high frequency event is one that we often have lots of experience with. Take driving for example. Most of us drive all the time, sometimes at very high speeds and on treacherous mountain roads. But how often do you get in a car accident? This is a high consequence activity that we have lots of experience with and generally can manage to do safely.

So what does this have to do with avalanches? As backcountry travelers our level of experience, training, and the systems that we employ can determine our ability to effectively choose appropriate terrain for the conditions. Backcountry travelers with decades of experience have seen many high frequency or high likelihood events over the years. Novices who have been traveling in the backcountry for only a couple years may have little experience with even the high frequency events. We generally do a good job at making decision in situations that we deal with on a regular basis. Examples of a high likelihood lower consequence problems are Storm Slab avalanches and Loose Dry slides or sluffs. Even on the high likelihood high consequence end, experienced travelers are still pretty good at making decisions. Take for example Persistent Slab avalanches during an active cycle. For someone who only has only a few years of experience this situation may sound terrifying and unmanageable. The best options for this person may be to avoid avalanche terrain in the backcountry. A backcountry traveler with many years of experience and training in these same conditions can understand the nuances of the problem, plan out an appropriate route that minimizes exposure to terrain prone to this avalanche problem, and effectively facilitate their group in making decisions that will keep them safe. It’s important to have an awareness of your experience level with different situations and recognize when you are dealing with conditions in which you are inexperienced.

Low likelihood high consequence situations are challenging to both novices and seasoned veterans. Currently most forecast zones around the state are dealing with avalanche problems involving deeply buried persistent weak layers that are difficult to trigger. If you do manage to hit the right spot and trigger one of these Deep Persistent Slab avalanches, the result could be a very large slide. This low likelihood high consequence situation is scary stuff. A resulting avalanche from these conditions is something that we don’t often experience and would leave little chance for survival. Last year’s Ptarmigan Hill and Sheep Creek accidents occurred during similar conditions. As backcountry travelers, we are bad at “managing,” or making decisions, in these kinds of conditions. We don’t have much experience with them and when we make a mistake the consequences are grave. We can easily be lulled into confidence and complacency when we don’t see signs of instability or recent avalanches. It’s important to remind ourselves of the consequences of the current conditions and our inability to “manage” them. Strive for conservative terrain selection, giving your group a very wide margin for error. Go to areas where you are confident that your group can make sound decisions and select appropriate terrain to stay safe.

–Josh Hirshberg