Item: Using Large Column Tests to Successfully Forecast Persistent Deep Slab Avalanches in the Central Sierra Nevada Mountains
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Title: Using Large Column Tests to Successfully Forecast Persistent Deep Slab Avalanches in the Central Sierra Nevada Mountains
Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA
Authors:
- Brandon Schwartz [ Tahoe National Forest Sierra Avalanche Center, Truckee, CA, USA ]
- Andy Anderson [ Tahoe National Forest Sierra Avalanche Center, Truckee, CA, USA ]
Date: 2016-10-02
Abstract: Forecasting of Persistent Deep Slab avalanches presents a unique and at times difficult problem for Backcountry Regional Forecasters, Guide Services, Highway Avalanche Mitigation Programs, Ski Area Avalanche Mitigation Programs and other avalanche forecasting operations. The addition of the Extended Column Test (ECT) and the Propagation Saw Test (PST) to the Avalanche Forecaster's toolkit has allowed for successful forecasting of Deep Slab avalanches. USDA Tahoe National Forest Sierra Avalanche Center (TNF-SAC) avalanche forecasters have created a framework for identifying when persistent weak layers are likely to contribute to deep slab avalanche problems under future loading conditions, often as much as two weeks in advance of the avalanche cycle. Using problematic near crust facet (NCF) layers observed during different winters, TNF-SAC forecasters were able to successfully forecast when these near crust facet layers would lead to deep slab avalanche problems. Signs of impending deep persistent slab conditions include: near crust facets (NCF) in the top 1.2 m of the snowpack, no current avalanches within the TNF-SAC forecast area, consistent ECTN results on these NCFs, and PST (End) results with less than 50% cut lengths. We present two case studies outlining the successful use of this deep slab avalanche forecasting framework.
Object ID: ISSW16_P4.26.pdf
Language of Article: English
Presenter(s):
Keywords: avalanche forecasting, persistent deep slab, Propagation Saw Test (PST), Extended Column Test (ECT), Sierra Nevada
Page Number(s): 1298-1301
Subjects: Propagation Saw Test (PST) Extended Column Test (ECT) avalanche forecasting
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