The effect of solar radiation on the release of dry slab avalanches is uncertain. This video discusses two situations in which solar radiation may increase the likelihood of dry slab avalanches: 1. Rapid solar warming when there is a persistent slab; 2. First direct sun on fresh dry snow. At 10:03 I said that radiation is less available in quantitative forecasts. However, nowadays radiation is more accessible. In Canada it is in the meteograms for the Mountain Weather Forecast. Bruce Jamieson, Thomas Exner, Bradford White, 2020. Sightly revised 2026 #solar #radiation #dry #slab #avalanche

Hopefully, this will spark discussion on how to classify avalanche size, especially for big avalanches. Based on a 2014 paper at the GeoHazards 6 conference and a corresponding 13 minute video. #avalanche #size #Size5 #SelkirkMountains #D-scale #destructivepotential

This video is about the first estimates of risk from rider triggered avalanches for various levels of avalanche danger. It assumes the skier does NOT use skilled route selection, i.e. the skier "center punches" the avalanche start zones. A presentation based on the paper: B. Jamieson, Schweizer, J., and Shea, C. 2009 Simple calculations of avalanche risk for backcountry skiing, International Snow Science Workshop. Davos, Switzerland. https://arc.lib.montana.edu/snow-science/objects/issw-2009-0336-0340.pdf

This 2011 video for advanced recreationists and practitioners identifies the five types of fracture character and shows the frequency of skier triggering on slopes that exhibited each type of fracture character in compression tests. #fracturecharacter #drops #pops #AlecvanHerwijnen #stabilitytest #snowpacktest #avalancheforecasting #nonplanarbreak #progressivecompression #resistantplanar #suddencollapse #suddenplanar van Herwijnen, A.F.G. and Jamieson, B., Fracture character in compression tests. Cold Regions Science and Technology, vol. 47, no. 1-2, pp. 60-68, 2007.

Case study of the warming period and avalanche cycle, 1-5 Feb, 2012, Purcell Mountains. On Feb 1, the snowpack was a "loaded gun". Many avalanches including deep dry slab avalanches occurred the first two days during which direct short-wave radiation hit the fresh storm snow. A few days later, a similar level of direct short wave radiation did not release avalanches. Thomas Exner prepared this case study. Doug Latimer of Shadow Light Productions shot and edited the video. #solar #short-wave #radiation #avalanche #slab #swarm

A brief how-to for common snowpack tests to locate and assess instabilities within the snowpack, presented by Mike Conlan. #ect #extendedcolumntest #rb #rutschblock #pst #propagationsawtest #compressiontest #ct #handsheartest #deeptaptest #dt #crackpropagation #avalancheforecasting Start times of tests in this video are as follows: 1:32 Compression Test 5:06 Deep Tap Test 7:28 Extended Column Test 10:54 Rutschblock Test 14:48 Propagation Saw Test 18:48 Shovel Shear Test 20:49 Hand Shear Test 22:11 Concluding remarks on initiation, propagation, and limitations. The specifications in this video are based on OGRS (Canadian Avalanche Association 2016). See https://vimeo.com/479569510 for the U.S. interpretation of the ECT, which was adopted in Canada in 2024. Fracture character video: http://vimeo.com/30996756

This video explains why the the PST was developed, shows two demonstrations of the propagation saw test, explains the usual interpretation of test results, and shows how it performed next to real avalanches and whumpfs over four winters. #crackpropagation #ASARC #interpretation #snowpacktest

Hopefully, this presentation will spark discussion on how to classify avalanche size, especially for big avalanches. Based on a paper presented at the 2014 Geohazards 6 conference in Kingston, Ontario. For the paper behind this presentation, search for: large avalanche selkirk reflections #geohazards6 #avalanche #size #destructivepotential #selkirkmountains #size5 #classification

Scott Thumlert presented this at the 2012 International Snow Science Workshop in Anchorage, Alaska. #avalanches #snow #stress #skier #snowmobile #snowpack #forecasting

An opinion on the much debated question about whether or not to do snowpack instability tests. Includes ECT technique and interpretation. Doug Chabot and Bruce Jamieson #snow #avalanche #snowpacktest #stabilitytest #avalancheforecasting #ect #extendedcolumntest #dougchabot #propagation