Item: USING TOTAL AVALANCHE VOLUME TO ASSESS CONSISTENCY IN OPERATION AVALANCHE SIZE REPORTING.
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Title: USING TOTAL AVALANCHE VOLUME TO ASSESS CONSISTENCY IN OPERATION AVALANCHE SIZE REPORTING.
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- M. Sydney White [ Rossland, BC, Canada ]
Date: 2026-09-28
Abstract: Avalanche size assignments often rely on visual estimates of key parameters such as destructive potential, debris extent, and avalanche mass, all of which are sensitive to inter-rater variability, observer experience, and vantage point. The 2024 update to the Canadian Avalanche Association Observation Guidelines and Reporting Standards (OGRS) introduced a method for estimating avalanche size based on debris volume. However, in practice, Canadian ski operations contributing to the InfoEx dataset rarely report debris depth. Instead, observations more commonly include avalanche length, width, and crown depth, enabling calculation of total avalanche volume rather than deposited debris volume. Given that avalanche size classes are defined on a logarithmic scale, it is reasonable to expect that size categories may still be distinguishable using total volume as a proxy. This study evaluates the feasibility of using total avalanche volume as a proxy for debris-volume-based size classification and assesses consistency in size reporting within a single guiding operation. At the selected operation, 99 avalanches were recorded between December 2025 and April 2026, of which 71 contained sufficient data to estimate total avalanche volume. Debris depth was not reported for any events. Calculated volumes were used to assign predicted size classes, which were then compared to sizes reported by guides. In 66 of the 71 avalanches, the predicted size exceeded the reported size, in some cases by as much as two size categories. Despite the logarithmic nature of the size scale, this discrepancy suggests inconsistency in field-based size assignments. Several limitations should be noted: avalanche geometry is often complex and terrain-constrained, making simple volume approximations imperfect, and all input parameters are subject to observational uncertainty. Overall, these findings highlight the limitations of current observational practices and reinforce the need for more standardized, measurement-based approaches. Encouraging practitioners to record debris depth within InfoEx would enable more accurate debris volume estimates, improve consistency in size classification, and support a better understanding of inter-rater variability in operational avalanche assessments.
Object ID: ISSW2026_P2.41.pdf
DOI: https://doi.org/10.15788/1790099001
Language of Article: English
Presenter(s): Sydney White
Keywords: Avalanche size, Avalanche volume, Avalanche volume deposits
Page Number(s): 1452 - 1457
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