Item: Monitoring Avalanches on Ca 120 in Yosemite National Park
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Title: Monitoring Avalanches on Ca 120 in Yosemite National Park
Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA
Authors:
- Sue Burak [ Snow Survey Associates, Crowley Lake, CA, USA ]
- Edward Bair [ Snow Survey Associates, Crowley Lake, CA, USA ]
Date: 2016-10-02
Abstract: Avalanches are a serious hazard to Yosemite National Park personnel during spring snow removal operations along California Highway 120, the Tioga Pass Road. The Road is the link to surrounding communities in California's Central Valley, the Eastern Sierra, and the urban centers on the West Coast. The Tioga Pass Road is closed during the winter months; snow removal operations begin on April 15. Road clearing operations often coincide with wet snow and glide avalanche activity especially along the granite dome dominated landscape in the Tuolumne Meadows area. Several glide and wet snow avalanche zones have been identified on north, northwest, west, and southerly aspects where glide cracks and glide avalanches occur annually. Glide occurs when the entire snowpack slowly slides downhill; glide cracks can form on slopes where glide rates vary. Glide avalanches are difficult to forecast and explosive mitigation techniques are mostly ineffective. While glide cracks may culminate in glide avalanches, they often widen and calve into blocks or melt out. During the 2016 winter season, Yosemite National Park authorized implementation of an avalanche monitoring program including installation of a weather station and a timelapse camera to monitor avalanche and glide activity. Installations occurred after the peak of glide avalanche activity, but valuable information was obtained from satellite images and in situ snowpack and avalanche observations. Continued monitoring will create a more complete record for this remote area of glide and other types of avalanche activity. This monitoring program will greatly augment existing knowledge about the location, timing, frequency and magnitude of avalanches along the Highway 120 corridor.
Object ID: ISSW16_P4.21.pdf
Language of Article: English
Presenter(s):
Keywords: avalanche, glide, Yosemite National Park, wet snow
Page Number(s): 1269-1274
Subjects: wet snow glide avalanches
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