Item: A POST-MITIGATION DEEP SLAB IN THE HOURGLASS COULOIR
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Title: A POST-MITIGATION DEEP SLAB IN THE HOURGLASS COULOIR
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Robert Griffith [ Jackson Hole Mountain Resort, Teton Village, WY, USA ]
- Mike Rheam [ Jackson Hole Mountain Resort, Teton Village, WY, USA ]
Date: 2026-09-28
Abstract: On the morning of January 1, 2026, Jackson Hole Mountain Resort saw its largest inbounds avalanche of the season in an area called the Hourglass Couloir. This D3.5 deep persistent slab with maximum depth around 10 feet was especially significant as it was remotely triggered by a snowcat pushing snow off the summit of Rendezvous Mountain 24 hours after explosive mitigation work was performed in the area. This paper introduces this high-elevation northeast facing terrain that is permanently closed to skiers, the distinct avalanche hazard mitigation techniques utilized for this unique zone, and the mission the day before which attempted unsuccessfully to trigger this slab. Early-season snow and avalanche activity leading up to the event will be considered and studied; and finally, past research into post-mitigation release will be examined and how it may help to understand this avalanche. This paper does not attempt to answer the mysterious question of why this avalanche occurred, but rather examine possible contributing factors while looking back and learning from the event.
Object ID: ISSW2026_P4.32.pdf
DOI: https://doi.org/10.15788/1790099328
Language of Article: English
Presenter(s): Robert Griffith
Keywords: incidents and case studies, post mitigation release, deep slab instability, ski area, explosives
Page Number(s): 1408 - 1414
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