Historic climate factors associated with major avalanche years on the Wasatch Plateau, Utah

This study examined climate factors associated with major avalanche years on the Wasatch Plateau in south-central Utah. Dendro-ecological methods were used to date the occurrence of avalanche events in 16 avalanche paths during the period of 1928–1996. From this information, the probability of avalanche occurrence in each path for each year was calculated, and used to distinguish major avalanche years. The resulting avalanche chronologies indicated that 14 large widespread avalanche events occurred on the Wasatch Plateau between 1928 and 1996. Logistic regression and classification tree analyses were used to examine relationships between climate variables and the probability of major avalanche years. The results of logistic regression analysis showed that mean January snowfall was significantly related (p<0.0001) to the probability of major avalanche years, although model correlations were extremely low. Variability in the data resulting from path differences, potential dating errors, the lack of complete historic climate records and the absence of snow pack information may have prohibited obtaining higher model correlations. The model, however, may help substantiate explanations of avalanche formation and initiation in the Intermountain region, or serve to generate alternative hypotheses for predicting major avalanche events. Avalanche professionals and land managers can use this information to augment conventional strategies for protection, forecasting, land use planning and management. This information also has broad ecological implications for increasing our understanding of major avalanches as important disturbances of Intermountain alpine and subalpine ecosystems.