Natural glide slab avalanches, Glacier National Park, USA: A unique hazard and forecasting challenge

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Abstract

In a museum of avalanche phenomena, glide cracks and glide avalanches might be housed in the “strange but true” section. These oddities are uncommon in most snow climates and tend to be isolated to specific terrain features such as bedrock slabs. Many glide cracks never result in avalanches, and when they do, the wide range of time between crack formation and slab failure makes them highly unpredictable. Despite their relative rarity, glide cracks and glide avalanches pose a regular threat and complex forecasting challenge during the annual spring opening of the Going-to-the-Sun Road in Glacier National Park, U.S.A. During the 2006 season, a series of unusual glide cracks delayed snow removal operations by over a week and provided a unique opportunity to record detailed observations of glide avalanches and characterize their occurrence and associated weather conditions. Field observations were from snowpits, crown profiles and where possible, measurements of slab thickness, bed surface slope angle, substrate and other physical characteristics. Weather data were recorded at one SNOTEL site and two automated stations located from 0.6-10 km of observed glide slab avalanches. Nearly half (43%) of the 35 glide slab avalanches recorded were Class D2-2.5, with 15% Class D3-D3.5. The time between glide crack opening and failure ranged from 2 days to over six weeks, and the avalanches occurred in cycles associated with loss of snow water equivalent and spikes in temperature and radiation. We conclude with suggest ions for further study.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Natural glide slab avalanches, Glacier National Park, USA: A unique hazard and forecasting challenge
Year Published 2006
Language English
Contributing office(s) Northern Rocky Mountain Science Center
Description 8 p.
Larger Work Type Conference Paper
Larger Work Subtype Conference Paper
Larger Work Title Proceedings of 2006 International Snow Science Workshop
First page 778
Last page 785
Conference Title 2006 International Snow Science Workshop
Conference Location Telluride, CO
Conference Date October 1-6, 2006
Country United States
State Montana
Other Geospatial Glacier National Park
Online Only (Y/N) N
Additional Online Files (Y/N) N