Item: Timing of Wet Snow Avalanche Activity: An Analysis from Glacier National Park, Montana, USA
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Title: Timing of Wet Snow Avalanche Activity: An Analysis from Glacier National Park, Montana, USA
Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska
Authors:
- Erich H. Peitzsch [ U.S. Geological Survey, Northern Rocky Mountain Science Center, West Glacier, Montana, USA ]
- Jordy Hendrikx [ Snow and Avalanche Laboratory, Montana State University, Bozeman, Montana, USA ]
- Daniel B. Fagre [ U.S. Geological Survey, Northern Rocky Mountain Science Center, West Glacier, Montana, USA ]
Date: 2012
Abstract: Wet snow avalanches pose a problem for annual spring road opening operations along the Going-to-the-Sun Road (GTSR) in Glacier National Park, Montana, USA. A suite of meteorological metrics and snow observations has been used to forecast for wet slab and glide avalanche activity. However, the timing of spring wet slab and glide avalanches is a difficult process to forecast and requires new capabilities. For the 2011 and 2012 spring seasons we tested a previously developed classification tree model which had been trained on data from 2003-2010. For 2011, this model yielded a 91% predictive rate for avalanche days. For 2012, the model failed to capture any of the avalanche days observed. We then investigated these misclassified avalanche days in the 2012 season by comparing them to the misclassified days from the original dataset from which the model was trained. Results showed no significant difference in air temperature variables between this year and the original training data set for these misclassified days. This indicates that 2012 was characterized by avalanche days most similar to those that the model struggled with in the original training data. The original classification tree model showed air temperature to be a significant variable in wet avalanche activity which implies that subsequent movement of meltwater through the snowpack is also important. To further understand the timing of water flow we installed two lysimeters in fall 2011 before snow accumulation. Water flow showed a moderate correlation with air temperature later in the season and no synchronous pattern associated with wet slab and glide avalanche activity. We also characterized snowpack structure as the snowpack transitioned from a dry to a wet snowpack throughout the spring. This helped to assess potential failure layers of wet snow avalanches and the timing of avalanches compared to water moving through the snowpack. These tools (classification tree model and lysimeter data), combined with standard meteorological and avalanche observations, proved useful to forecasters regarding the timing of wet snow avalanche activity along the GTSR.
Object ID: issw-2012-884-891.pdf
Language of Article: English
Presenter(s): unknown
Keywords: wet snow avalanches, glide avalanches, glacier national park, avalanche forecasting
Page Number(s): 884-891
Subjects: avalanche forecasting wet snow avalanches going-to-the-sun road
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