Avalanche Release and Snowpack Observations

AvalancheRelease_ISSW16_Schewizer.pdf

Avalanche Release 101

Schweizer et al. 2016

Avalanche Release Resources

Our ability to evaluate the avalanche hazard relies on our understanding of how the mountain snowpack develops over terrain. This includes understanding how snow layers become relatively strong or weak, and it includes relating snowpack instability to a loss of cohesion of near-surface snow or to propagating cracks through weak layers. This is knowledge of how avalanches form and how avalanches release.

Understanding the mechanism of avalanche release improves our ability to:

• Determine where (distribution) and when (timing) avalanches could occur.

• Determine the probable extent and consequence resulting from avalanche release.

• Better understand which field observations and tests provide valuable clues that describe the avalanche problem.

Avalanche release should be of principal interest to practitioners. Researchers from around the world are continuing to model and study the mechanisms associated with each type of avalanche. Open or or download and read the corresponding resource, Avalanche Release 101 by Schweizer et al. from the 2016 ISSW lays a foundation for understanding dry-snow slab release and can serve as a professional resource for you in the future.

Toolbox Approach To Snowpack Observations

Colin Zacharias 2015

Snowpack observations can help us to delineate how each individual layer interacts within the greater snowpack. They are helpful in determining strength and structure and can aid in determining critical factors for avalanche release. Avalanche professionals need to understand the value and limitations of snowpack tests and observations. The ToolBox Approach article summarizes these and provides a process by which to apply tests in the field.

Craftsmanship: It is critical that all snowpack tests (even quick/ hasty tests) are done with the highest standard of craftsmanship. This ensures replicable results and eliminates false positives.

Parameters: Each test has certain parameters for accurate results. Certain tests are designed to test for sheer (shovel shear test), some test for compression (compression test, deep tap), and some test for propensity for propagation (Extended column test, propagation saw test). Knowing the parameters for each test will help yield the most accurate results.

Results: Not every result should be treated equally. Make sure to check your work (did you cut all sides of the column, was the column even throughout). Once you have determined that the craftsmanship was up to standard, then it is time to replicate the data. Make sure to run another test to see if the results stand up.

Tool Box: Once you have determined something like weak layer identification, then it is important to continue on in the toolbox to test for shear strength, fracture initiation (compressive strength), and propensity for propagation. Make sure you are using the appropriate tools and applying them to the appropriate problems given the distribution and character of the problem. Assignment:

Assignment:

Read the corresponding article originally published in The Avalanche Journal by Colin Zacharis to help refine your understanding of targeting layers for testing. Colin served as AIARE's Technical Director until 2018 and provides excellent insight into the concept of craftsmanship in snowpack tests.

In your student journal document the following:

What did you learn from the article about craftmanship, relevancy, how to use the Toolbox.

You may find it useful to print the ToolBox Approach For Investigating Layers graphic (Fig 3) on page 6 and create a small laminated reference card to place in your field book during the course.

Activity Time:

Snowpack observations such as grain identification are a skill every practitioner continuously relies on to feed the forecasting cycle and gain insight into the behavior of avalanches. Take a few minutes to complete this flashcard activity. Prior to the course, practice identifying grains and capturing your own images to add to your personal catalog.

The following videos produced by renowned researcher and alacritous thinker, Dr. Bruce Jamieson, provide some additional visualization for avalanche release in dry slab avalanches. Jamieson's ability to cut to the heart of the extensive research performed by him and others and provide succinct overviews is astonishing. Furthermore, he has a penchant for asking practitioners to stop and think about his analysis of the work performed by him and his colleagues, and to come up with their own conclusions and even challenge their findings. We include these videos as a waypoint on your journey of understanding snowpack properties related to avalanche release. They are not complete and the body of research is vast and continues to grow. As a professional on this course, it is up to you to assimilate new info, read source materials, ask your instructor team questions to improve your understanding and find ways to implement the theory in your own practice.

Get out and practice.

Spending time in the snow with an intention to exhibit good craftsmanship in snow profiles is a great way to build a routine you can employ on course. Your instructors will undoubtedly provide you with additional tips and techniques to improve craftsmanship and save time, but starting now with structured practice will serve you well in the future.

We've include two additional resources for download. The AIARE Profile Example + Template are to be printed off and used to get you accustomed to our current format for tabular profile recording. This may be different than what you have used in the past, but the basics are the same. Additionally, we have included a helpful resource practitioners can use to help them determine which layers are of greatest concern and may warrant additional scrutiny. Dr. Bruce Jamieson and his colleague Jurg Schweizer put together a fascinating paper highlighting how we can use certain structural indices, also known as "Yellow Flags", to guide us towards illuminating the weak layers under our feet in a new light.

AIARE Fieldbook Profile V4.pdf

AIARE Fieldbook Profile Template

Download and use to practice ahead of your course.

Using a Checklist in Profiles Jamieson

Using a Checklist to Assess Manual Snow Profiles

Jamieson and Schweizer 2005

PRO 1 Profile Review

You may have just taken your PRO 1, or it may have been a while. Refresh your memory on the skills trained and evaluated on the Snow Profile Exam. We will not examine you on the PRO 2. However, we encourage all participants to feel comfortable with their snow profile organization and time management. We often move quickly through the field gathering key observations and may only focus on a few targeted items or tests each time we dig.

Introduction

Snowpack Observations

Snowpack Tests

Back

Page updated

Report abuse