Analysis of long-term weather, snow and avalanche data at Glacier National Park, B.C., Canada

- Seasonal analysis of long term weather and avalanche data was analyzed for Glacier National Park (Rogers Pass), B.C. Canada.
- Significant increasing air temperature trends were found for the mid season between December and February.
- Decreasing trends of 24-hour new snow amounts and consequently snow height were found.
- Increasing formation of early season rain crusts was found for recent years, indicating a potential regime shift.
- Long term changes of avalanche activity remain unknown.

Long-term changes of the global climate system have been observed. However, the effect of long-term changes in the climate system on avalanche hazard in mountainous areas remains inconclusive. For this study we analyzed long-term weather, snow cover, and avalanche data from Glacier National Park. Weather and snow cover data were measured at two sites (1315 m and 1905 m a.s.l.). The avalanche data were observed along the section of the Trans Canada Highway within the park. Meteorological data were analyzed by winter season, i.e. early, mid and late winter, represented by three-month periods between September and May. Increasing trends were found for the mean seasonal air temperature at both stations during the mid season. Trends for the solid precipitation rate were not significant, indicating no trend towards more rain events. Decreasing trends of the maximum snow depth were only found for the lower elevation station at Rogers Pass for the mid and late season, which is consistent with decreasing trends for all seasons of the mean 24-hour new snow amounts at the lower elevation and for the mid season at the higher elevation station at Mt. Fidelity. Due to uncertainty arising from changes in explosive control, we draw no conclusions regarding the regional change of avalanche activity. However, the weather and snowpack trends observed in Glacier National Park are consistent with longer time series from mountains with similar latitudes and elevations in France and Switzerland.