The size of a specific avalanche is assessed with the more visual method and a more quantitative method. Uploaded 2024-04-05. CC BY-ND.

How avalanche workers measure the density of snow layers as thin as 4 cm.

Weak snowpack layers formed by near surface faceting were under-recognized prior to Karl Birkeland's field studies and publications in 1998. This story from recognition of near surface faceting to forecasting and public communication is told by Karl Birkeland, Doug Chabot, Ed Adams, Mark Staples, Mike Cooperstein and Ethan Greene. CC BY-ND

The three chapters of this video are also available separately at https://www.brucejamieson.ca/videos-snow-avalanche-science 2:32 Chapter 1 - Formation and spatial variability 13:00 Chapter 2 - How buried surface hoar and propagation propensity change 20:10 Chapter 3 - Choosing terrain and how pros track layers Simon Horton and Bruce Jamieson, uploaded 8 Nov 2023. CC BY-ND. For videos on the following topics briefly mentioned in the video, follow the links: - Rider triggering (including triggering from a thin area) and crack propagation in weak layers. https://vimeo.com//773056211 - Surface energy exchange and near surface faceting. https://vimeo.com/243958459 For help with the video, we thank Greg Johnson, Marc Piché, Dave Gauthier, Karl Klassen, Doug Chabot, John Buffery, Bill Mark, Ryan Buhler, Steve Conger, Brad Stanton, Dan Miller, Ed Adams & past ASARC students and staff. Key references: 1. S. Horton and Jamieson, B. 2016. Modelling hazardous surface hoar layers throughout western Canada with a coupled weather and snow cover model. Cold Regions Science and Technology 128, 22-31. 2. B. Jamieson and Schweizer, J. 2000. Texture and strength changes of buried surface hoar layers with implications for dry snow-slab avalanche release. Journal of Glaciology 46(152), 151-160.

Chapter 3 is about choosing terrain and how pros track persistent weak layers. Simon Horton and Bruce Jamieson, uploaded 25 October 2023. CC BY-ND. For more on the following topics briefly mentioned in the video, follow the links: - Rider triggering (including triggering from a thin area) and crack propagation in weak layers. https://vimeo.com//773056211 - Surface energy exchange and near surface faceting. https://vimeo.com/243958459 For help with the video, we thank Greg Johnson, Marc Piché, Dave Gauthier, Karl Klassen, Doug Chabot, John Buffery, Bill Mark, Ryan Buhler, Steve Conger, Brad Stanton, Dan Miller, Ed Adams & past ASARC students and staff. Key references: 1. S. Horton and Jamieson, B. 2016. Modelling hazardous surface hoar layers throughout western Canada with a coupled weather and snow cover model. Cold Regions Science and Technology 128, 22-31. 2. B. Jamieson and Schweizer, J. 2000. Texture and strength changes of buried surface hoar layers with implications for dry snow-slab avalanche release. Journal of Glaciology 46(152), 151-160.

Chapter 2 of Some science behind surface hoar and its insidious avalanches - Changes to buried surface hoar and its propagation propensity. For more on the following topic briefly mentioned in the video, follow the link: - Rider triggering (including triggering from a thin area) and crack propagation in weak layers. https://vimeo.com//773056211 Simon Horton and Bruce Jamieson, uploaded 28 October 2023 For help with the video, we thank Greg Johnson, Marc Piché, Dave Gauthier, Karl Klassen, Doug Chabot, John Buffery, Bill Mark, Ryan Buhler, Steve Conger, Brad Stanton, Dan Miller, Ed Adams & past ASARC students and staff. Key references: 1. S. Horton and Jamieson, B. 2016. Modelling hazardous surface hoar layers throughout western Canada with a coupled weather and snow cover model. Cold Regions Science and Technology 128, 22-31. 2. B. Jamieson and Schweizer, J. 2000. Texture and strength changes of buried surface hoar layers with implications for dry snow-slab avalanche release. Journal of Glaciology 46(152), 151-160.

Chapter 1 - Formation and spatial variability For videos on the following topics briefly mentioned in the video, follow the links: - Rider triggering (including triggering from a thin area) and crack propagation in weak layers. https://vimeo.com//773056211 - Surface energy exchange and near surface faceting. https://vimeo.com/243958459 Simon Horton and Bruce Jamieson, uploaded 23 October 2023 For help with the video, we thank Greg Johnson, Marc Piché, Dave Gauthier, Karl Klassen, Doug Chabot, John Buffery, Bill Mark, Ryan Buhler, Steve Conger, Brad Stanton, Dan Miller, Ed Adams & past ASARC students and staff. Key references: 1. S. Horton and Jamieson, B. 2016. Modelling hazardous surface hoar layers throughout western Canada with a coupled weather and snow cover model. Cold Regions Science and Technology 128, 22-31. 2. B. Jamieson and Schweizer, J. 2000. Texture and strength changes of buried surface hoar layers with implications for dry snow-slab avalanche release. Journal of Glaciology 46(152), 151-160.

In February 2000, Crane Johnson and ASARC colleagues measured the speed of a whumpf with geophones.This measurement triggered theory, modeling and field studies into avalanche release. Crane Johnson, Greg Johnson, Karl Birkeland, Bruce Jamieson. Uploaded 29 Sept. 2023. This is Episode 1 of Avalanche Research Stories. #MoreScienceThanNecessary CC BY-ND.

This video outlines - for a wide audience - the current understanding of how rider-triggered and natural avalanches start. Bruce Jamieson, Karl Birkeland and Ron Simenhois, January 2023. CC BY-ND. Key sources: Schweizer, J., B. Reuter, A. van Herwijnen, J. Gaume. 2016. Avalanche release 101, Proceedings of the 2016 International Snow Science Workshop in Breckenridge, CO, USA. Gaume, J., van Herwijnen, A., Gast, T., Teran, J., Jiang, C. 2019. Investigating the release and flow of snow avalanches at the slope-scale using a unified model based on the material point method. Cold Region Science and Technology 168. Trottet, B., Simenhois, R., Bobillier, G.; Bergfeld, B., van Herwijnen, A., Jiang, C., Gaume, J. 2022. Transition from sub-Rayleigh anticrack to supershear crack propagation in snow avalanches. Nature Physics 18.

A cheesy animation of skier triggering, showing the crack in the weak layer then at the crown. CC BY-ND