Item: Forecasting factors for skier-triggered avalanches at a helicopter skiing operation
Title: Forecasting factors for skier-triggered avalanches at a helicopter skiing operation
Proceedings: Proceedings of the 2000 International Snow Science Workshop, October 1-6, Big Sky, Montana
Authors: Alan S.T. Jones, Bruce Jamieson, Mike Wiegele, Department of Civil Engineering, University of Calgary, Calgary, Alberta, Canada, Department of Geology and Geophysics, University of Calgary, Calgary, Alberta, Canada, Mike Wiegele Helicopter Skiing
Abstract: To forecast skier-triggered avalanches, stability, snowpack and meteorological variables, and records of previous avalanche activity are typically used. The relative importance of, and interaction between, variables used to forecast skier-triggered avalanches have received little attention. This study analyzes the influence of forecasting variables at a heli-skiing operation in the Columbia Mountains of British Columbia, Canada. Forecasting variables are individually assessed using rank correlations to identify which are most relevant for forecasting the potential for skier-triggered slab avalanches. The variables showing the strongest forecasting potential include: the largest skier-triggered avalanche observed on the previous one and two days, 24-hour snowfall and precipitation, storm snow, height of snowpack, and the number of days since December 1. The physical processes that relate these variables to skier-triggered avalanches are discussed. The predictive potential of combined forecasting variables is assessed using a classification tree model, Verification of the model with the last two years of data shows that the model predicts relatively large avalanches approximately two-thirds of the time.
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Keywords: avalanches, avalanche forecasting, avalanche triggering, skier triggering
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