International Snow Science Workshop Proceedings - Montana State University Library

Item: On Indicator Path Avalanches for Local Avalanche Forecasting

• • Title: On Indicator Path Avalanches for Local Avalanche Forecasting

    Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska

    Authors:

    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Claudia Alig  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Christoph Mitterer   [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]

    Date: 2012

    Abstract: Avalanches are clear signs of instability and thus often considered as the best predictor for further events. In fact, avalanches that release at the beginning of a period with high avalanche activity are called indicator path avalanches. We evaluate whether such indicator path avalanches exist and whether they can be used to improve local avalanche forecasting. Long-term avalanche occurrence data for three areas in Switzerland were analyzed. In the region of Davos, the Salezertobel avalanche was found to have a precursor function, but only if it was of a certain size. In the Urseren valley which runs about west to east from Realp to Andermatt, two indicator path avalanches were found: the Böschenlaui on the northern slopes of the valley and the Lochtal-, Lauital- and Spitzegglaui avalanches on the southern slopes. In the Upper Engadine valley, four adjoining avalanches were considered and analyzed as a single indicator path avalanche. Results suggest that even if indicator path avalanches can predict other avalanches to follow, the quality of the forecast remains rather poor. Whereas there is a good chance that the release of an avalanche in an indicator path is followed by other avalanches, there are too many situations when some of these avalanches release but not the one in the indicator path. Based on our analysis, it seems not feasible to forecast other large avalanches simply based on the avalanche occurrence in an indicator path – still the size of the indicator path avalanche was indicative of the magnitude of the subsequent avalanche activity.

    Object ID: issw-2012-051-054.pdf

    Language of Article: English

    Presenter(s): unknown

    Keywords: avalanche path, snow depth,prediction methods, avalanche awareness

    Page Number(s): 51-54

    Subjects: natural avalanche paths avalanche prediction

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