Avalanche Climatology of Alyeska, Alaska, U.S.A.

Abstract

Data covering over 20 winters at Alyeska Ski Resort, located in south-central Alaska, provide a unique opportunity to examine avalanche climatic characteristics for the region. Averages of climatic, snowpack, and avalanche data for numerous variables indicate that a variety of avalanche climatic conditions ranging from coastal to continental can occur. However, averaged conditions generally tend to be slightly more coastal, resembling conditions similar to Alta, Utah, and Mount Hood, Oregon, as a result of heavier snowfall and higher water equivalent, but relatively lower temperatures than other coastal stations. Snowfall and water equivalent variables most closely correlate with avalanche activity, but temperature, snow density, and snow depth play important roles during some winter months. Composite difference maps of 700-mb heights show that anomalies in the northeastern Pacific Ocean are important in explaining abnormally high and low numbers of avalanches, representing storm activity related to the Aleutian low. Height anomalies off the west coast of North America and east of Alyeska, representing variations of the Pacific subtropical high and mid-winter ridging, also play important roles.