Overview

Winter recreation in the mountains is great fun, but it is not without risk. Knowing as much as possible about the weather, terrain, and snow conditions that contribute to avalanches are essential for safe backcountry travel. At the conclusion of this learning activity, you should be able to describe some of the weather, terrain, and snow conditions that have contributed to avalanche fatalities in the Wasatch backcountry and hopefully have a greater awareness of potential issues when you travel in avalanche terrain.

Instructions

Utilize the information located in the Scenario and Key Concepts to answer the questions located in this activity. You may refer to your textbook and notes to help you work through the assigned questions if desired. You will have two attempts to complete this activity. The highest grade will automatically be recorded. Once you have submitted your activity for a second time, you will be able to see the correct answers. Discuss with your instructor if you have questions about your answers or feedback.

Activity is due Sunday, by 11:59 p.m. MT

Submission and Assessment Guidelines

You will complete the quiz associated with this scenario within Canvas. For help on how to take a quiz in Canvas, review How do I take a quiz.
This learning activity is worth 10 points toward your final grade.

Scenario

You are an avid winter recreationist who has just moved to Salt Lake City from Pennsylvania where avalanches are non-existent. You are excited to explore your new backyard but have heard that there can be avalanche hazards in the Wasatch Mountains. You have been reading Staying Alive in Avalanche Terrain by Bruce Tremper and are planning on taking a level I avalanche class in the near future, but are interested in learning more about what has contributed to local avalanche accidents.

Key Concepts

a. Avalanche Triangle

The avalanche triangle is the graphical depiction of the key factors contributing to avalanche danger: Terrain, Snowpack, Weather, and Human Factors.

Avalanche triangle of weather, terrain, and snowpack, with human factors in the middle
Figure 1. The Avalanche Triangle (source: snowbrains.com).

We have covered to some degree snowpack and the role of a weak layer, terrain, and the importance of slope angle, and weather, which can increase avalanche hazard or serve as a trigger through heavy snow or rain, wind-deposited snow, or a rapid temperature increase. Human factors are also important in avalanche accidents since they can cloud judgment or cause us to not fully recognize risk, but we will examine these in greater depth in the next module.

The contributions of Terrain, Snowpack, and Weather are very apparent in avalanche accident summaries provided by the Utah Avalanche Center and available at this link. Although these summaries describe the tragic loss of life or lives, they provide valuable lessons about the factors that contribute to avalanche accidents, especially in the Wasatch Mountains as well as elsewhere in the state of Utah.

b. Avalanche Accidents

We will focus specifically on the following accidents:

Tibble Fork (8 February 2014)

A snowshoer was killed by a small avalanche just north of Tibble Fork Reservoir in American Fork Canyon. The accident report is available here.

Gobblers Knob (21 January 2016)

A skier in a guided group was killed in an avalanche in the Whitesnake slide path on the south side of Gobblers Knob above Big Cottonwood Canyon. The accident report is available here. Be sure to watch the video.

Square Top (30 January 2021)

A skier in a group of two skiing the backcountry from Chair 9990 at the Canyons Village area of Park City Mountain Resort was killed in an area known as Square Top. The accident report is available here.

c. Avalanche Rescue Gear

Avalanche rescue gear sometimes discussed in the reports includes a beacon, shovel, probe, and airbag pack. The beacon, shovel, and probe are considered essential for backcountry travel and are pictured in Figure 2 (the probe folds, but once extended, is about 8 to 10 feet long). A beacon, also known as a transceiver, is worn by all members of a party and sends out a signal that enables party members, if well trained, to quickly locate the general location of a buried companion. The probe is then used to pinpoint the location of the buried companion beneath the snow. Finally, a shovel is needed to dig through the snow and penetrate avalanche debris, which is often very dense and hard. For details, see this Backcountry Access Rescue Series.

Photos of an avalanche beacon, shovel, and probe

Figure 2. Examples of avalanche beacons (a.k.a., transceivers), probe, and shovel. Courtesy Utah Avalanche Center.

Also discussed is an avalanche airbag pack, pictured in Figure 3. Avalanche airbag packs contain a deflated airbag and either a compressed cylinder of gas or a high-speed fan. If an avalanche occurs, the winter recreationist can pull on a handle and the cylinder or fan rapidly inflates the airbag, which in some situations can help them stay on top of the snow or protect them from obstacles like trees.

Photo of an airbag pack
Figure 3. Avalanche airbag pack. Courtesy Utah Avalanche Center and Backcountry Access.

Citations

Scenario:

Utah Avalanche Center
- Citation: Utah Avalanche Center (n.d.). Avalanche fatalities.
Accident: Tibble Fork
- Citation: Utah Avalanche Center (n.d.). Accident: Tibble Fork.
Accident: Gobblers Knob
- Citation: Utah Avalanche Center (n.d.). Accident: Gobblers Knob.
Accident: Square Top
- Citation: Utah Avalanche Center (n.d.). Accident: Square Top.
Avalanche Rescue Series: Beacon Searching 101
- Citation: Backcountry Access. (2019, September 3). Avalanche rescue series: Beacon searching 101 [Video]. YouTube.

Images:

Key Concepts

Figure 1. The Avalanche Triangle
- Citation: Malott, C. (2020, August 28). Backcountry safety 101: Understanding avalanche terrain. Snow Brains.
Figure 2. Examples of avalanche beacons (aka, transceivers), probe, and shovel.
- Citation: KBYG: Know Before You Go. (n.d.). Carry avalanche rescue gear in the backcountry. Utah Avalanche Center.
Figure 3. Avalanche air bag pack.
- Citation: Utah Avalanche Center and Backcountry Access. (n.d.). Avalanche air bag pack. Utah Avalanche Center.