A probabilistic technique for exploring multi-scale spatial patterns in historical avalanche data by combining GIS and meteorological nearest neighbors with an example from the Jackson Hole Ski Area, Wyoming

3 U.S. Forest Service National Avalanche Center Abstract: Many ski areas, backcountry avalanche centers, highway departments, and helicopter ski operations record and archive daily weather parameters and the resulting avalanche activity. This paper proposes a new probabilistic method to allow avalanche forecasters to better utilize their historical weather and avalanche data by incorporating a Geographic Information System (GIS) with a modified meteorological nearest neighbors approach. This approach utilizes concepts from Geographic Visualization (GVis) and Knowledge Discovery in Databases (KDD). The resulting interactive database tool allows avalanche forecasters to visually explore regional spatial patterns of avalanche activity at multiple scales. This technique allows the correlation between weather parameters and the spatial pattern of avalanche activity. An example of this method was implemented using 23 years of historical avalanche data from the Jackson Hole Ski Area with over 10,000 avalanche events to analyze the effect of new snow, wind speed, and wind direction on the spatial patterns of avalanche activity. Patterns were found at the slide path scale and for sub-regional groups, but not for the entire region as a whole, or when slide paths were grouped by aspect categories.