CAIC: Colorado Avalanche Information Center

2022/01/08 - Colorado - North Star Mountain, Hoosier Pass

Published 2022/01/14 by Jason Konigsberg, Will Barrett - Colorado Avalanche Information Center


Avalanche Details

  • Location: North Star Mountain, Hoosier Pass
  • State: Colorado
  • Date: 2022/01/08
  • Time: Unknown
  • Summary Description: 2 snowshoers and a dog caught, buried, and killed
  • Primary Activity: Hiker
  • Primary Travel Mode: Snowshoe
  • Location Setting: Backcountry

Number

  • Caught: 2
  • Partially Buried, Non-Critical: 0
  • Partially Buried, Critical: 0
  • Fully Buried: 2
  • Injured: 0
  • Killed: 2

Avalanche

  • Type: HS
  • Trigger: AI - Snowshoer
  • Trigger (subcode): u - An unintentional release
  • Size - Relative to Path: R3
  • Size - Destructive Force: D2
  • Sliding Surface: O - Within Old Snow

Site

  • Slope Aspect: E
  • Site Elevation: 11800 ft
  • Slope Angle: 35 °
  • Slope Characteristic: Concave Slope

Avalanche Comments

This avalanche occurred on a steep, wind-loaded, east-facing slope near treeline. It was a hard-slab avalanche, triggered by a snowshoer, medium-sized relative to the path and produced enough destructive force to bury, injure, or kill a person (HS-AIu-R3D2-O). The avalanche ran 100 vertical feet and was 370 feet wide. The crown face of the avalanche was 3 to 10 feet high.The avalanche broke near the ground on faceted crystals 1 to 2 mm in size. The avalanche debris averaged 6 feet deep and partially buried a Forest Service road, open to motorized travel in the summer. The road was mostly drifted in by recent snow and wind. The runout angle of the avalanche was 26 degrees. The average steepness of the slope in the starting zone was 35 degrees, though some portions of the slope were as steep as 38 degrees.

Backcountry Avalanche Forecast

The Colorado Avalanche Information Center (CAIC) rated the backcountry avalanche danger in the Vail & Summit County zone at Considerable (Level 3 of 5) at all elevations on the day of the accident. Persistent Slab avalanches were the first avalanche problem in the forecast, on west through north to southeast aspects. The likelihood of triggering was Likely, with the potential size Large to Very Large. Wind Slab avalanches was the second problem, on northeast, east, and southeast aspects near and above treeline. The likelihood of triggering was Possible, and potential size Small to Large. The summary statement read:

Recent widespread natural avalanche activity tells us that conditions are dangerous. You can easily trigger an avalanche large enough to bury or kill you, and you can trigger them from a distance or from below. New snow and high winds drifted snow onto easterly slopes. This additional load makes it easier for you to trigger a large avalanche that breaks near the ground on weak layers. Watch out for areas where the slabs from the holiday storm will be thinner, and it will be easier for you to trigger an avalanche. These include rock outcroppings, convex rollovers, and shallow spots near ridgelines and at the bottom of slopes. You can also trigger a smaller avalanche in drifted snow that steps down into these weak layers. Drifted snow will feel stiff and have rounded, smooth, and pillow-like features. You can find wind-drifted snow below ridgelines, around rock outcroppings, and on the sides of gullies. You can find safer riding on slopes less than 30 degrees that do not have steep slopes above them.

Weather Summary

The Natural Resources Conservation Service Hoosier Pass SNOTEL site is 0.7 miles east of the accident site at an elevation of 11,400 feet. Breckenridge Ski Resort reports daily snowfall from a location 8 miles north of the accident site at an elevation of around 11,200 feet. Snow began to accumulate for the season by mid October. On October 31, the Hoosier Pass SNOTEL site recorded a snow depth of five inches with 1.1 inches of snow water equivalent (SWE). That was 65% of the median SWE for the 1990 to 2020 reference period. Snow accumulated in three storms during November, but at the end of the month the total SWE at the site was 67% of the 30-year median. Between December 23 and January 1, Breckenridge Ski Resort reported 42 inches of snowfall and the Hoosier Pass SNOTEL recorded 2.0 inches of SWE. On December 31, 2021, there was 27 inches of snow with 5.4 inches SWE, 84% of the 30-year median. Another storm January 4 to 7 brought 15 inches of snow to Breckenridge Ski Resort. At the Hoosier Pass SNOTEL, the storm increased snowpack depth to 37 inches with 1.2 inches of SWE, bringing the total SWE to median values on January 7.

Breckenridge Ski Resort maintains a high-elevation weather station on Peak 6, 9 miles north of the accident site at an elevation of 12,573 feet. Winds were westerly with sustained speeds 30 to 40 miles per hour from mid to late December. Strong westerly winds blew from January 4 through 8. Daily average wind speeds were around 40 mph at the station, with a peak gust of 92 mph on January 7.

The weather was stormy on the day of the accident. It was snowing and very windy. Visibility was extremely limited.

Snowpack Summary

The beginning of the season was very warm and dry. Below normal snowfall in October and November produced a layer of very weak, faceted snow. Increased snowfall in December and early January built dense layers over the weak foundation. Strong westerly wind during the second half of December drifted snow and formed very thick and dense wind drifts near and above tree line. The crown face of the avalanche was three to ten feet deep and composed of wind-drifted snow.

There was a widespread avalanche cycle in Colorado that began on December 23 and continued into  the new year. The CAIC documented 134 avalanches in the Vail & Summit County zone during this avalanche cycle, including 29 human-triggered avalanches.The majority of the human-triggered avalanches occurred near and below tree line on north through east to southeast aspects. The fatal avalanche was triggered near treeline on an east-facing slope.

Events Leading to the Avalanche

Hikers 1 and 2 left Colorado Springs on the morning of Saturday, January 8 to go snowshoeing near Breckenridge.

Accident Summary

There were no witnesses to the avalanche.

Rescue Summary

Hiker 1 had plans to meet friends in Colorado Springs for a day of skiing at Breckenridge on Sunday morning. His friends did not get replies to their text messages on Saturday, and Hiker 1 did not show up to the meeting on Sunday morning. Friends of Hiker 1 and Hiker 2 checked with each other and none of them had heard from the pair. With location sharing, Hiker 2’s sister was able to locate Hiker 2’s cell phone near Hoosier Pass. The friends alerted authorities about the overdue hikers on Sunday morning.

Authorities suggested Hiker 1’s friends look for his car at trailheads near Hoosier Pass. They found his car at the Hoosier Pass trailhead and an organized search began. While en route to the Hoosier Pass trailhead, a Summit County Sheriff’s deputy saw a large avalanche northwest of the pass. This avalanche was very close to the coordinates provided by Hiker 2’s sister. A Flight for Life helicopter flew over the avalanche and the crew saw tracks going into the avalanche debris but not coming out. The search then became an avalanche rescue. The helicopter deployed an avalanche rescue team from the Summit County Rescue Group with a Colorado Rapid Avalanche Deployment validated dog to the avalanche site. The team quickly located the two hikers and their dog around 3:00 PM on Sunday. They were completely buried near the southern side of the toe of the avalanche debris.

Comments

All of the fatal avalanche accidents we investigate are tragic events. We do our best to describe each one to help the people involved and the community as a whole better understand factors that may have contributed to the outcome. We offer these comments in the hope that it will help people avoid future avalanche accidents

There were no witnesses to this accident and the only information we have about the events of the day come from tracks in the snow and discussions with friends of the two hikers. From these discussions we know that neither of them had avalanche safety training or taken an avalanche awareness class. We know that they did not leave a trip plan with their friends or family. We know that they were not carrying avalanche rescue equipment (avalanche transceiver, probe pole, and shovel).

Obtaining current information on avalanche conditions is part of preparing for a day in the Colorado mountains. On the day of the accident, the CAIC forecast described dangerous conditions and emphasized that avalanches could be triggered from the bottom of slopes. With those conditions, avoiding steep slopes is very important for safer travel. At other times with generally safe avalanche conditions, it may be reasonable to cross under, or even on, those same steep slopes.

Their tracks indicate they were following the Forest Service road from Hoosier Pass to Crystal Lake. The road starts innocuously from Hoosier Pass without any steep slopes above. It is easy to imagine how the pair went out for a casual snowshoe with their dog and unknowingly hiked into avalanche terrain and a very dangerous situation.

The pair could have made a series of choices if they had recognized they were entering avalanche terrain. They could have avoided the steep slopes, either identifying the slopes as they traveled or in the planning process before hiking. The weather on the day of the accident probably made it difficult for the two to see that they were drifting off of the road and under a short, but quite steep terrain feature. Trip and route planning can mitigate the effects of bad weather by identifying areas to avoid in advance. Likewise, identifying avalanche terrain in advance allows you to more easily avoid it.

Their burial location indicates they were traveling close together. If they had known about the hazard it would have been safer to travel through any avalanche area one at a time. That exposes only one person to the avalanche hazard. This would allow the remaining group to conduct a rescue if one person gets caught in an avalanche.

This accident highlights the importance of trip planning and basic avalanche awareness if you are in Colorado’s mountains, regardless of your activity. Similar to a basic understanding of ocean currents before swimming, or how rules of the road allow us to travel in vehicles safely much of the time, avalanche awareness and trip planning are important for traveling safely in the mountains. Along with many avalanche centers in North America, the CAIC provides the free Know Before You Go (KBYG) avalanche awareness program. KGYB will help you understand how and why avalanches occur and how you can have fun in the mountains and avoid avalanches.

Even a short hike from a busy trailhead requires planning. There are many steep, avalanche-prone slopes in the Colorado mountains. Identifying terrain to avoid under current conditions is an important part of planning. You should always check the avalanche forecast so you know the level and location of the hazard and choose a route that maintains the level of risk you are both willing and prepared to face. Using safe travel methods, such as sticking to low-angle slopes and traveling one at a time, are important. Carrying the right equipment is also important, and for avalanches the bare minimum is an avalanche-rescue transceiver, and probe pole, and shovel. In any season, leaving a trip plan with someone outside of your group will help other people when they start looking for you.

A backcountry skier triggered and was caught in a similar avalanche on November 2, 2018

Media

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Snowpits

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Figure 11: Crown profile observed January 9 at a thin portion of the crown face.
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Figure 12: Crown profile observed January 9 at a location where the crown was at the average thickness of five feet.