Examining the Relationship Between Snowfall and Wildfire Patterns in the Western United States

Spatial and temporal patterns of snowfall influence future moisture availability, plant growth, and soil moisture. Therefore winter and spring snowfall may influence summer wildfire patterns. We conducted an examination of the spatial and temporal relationships and correlations between snow cover and wildfire from 1986 through 1996 in the 11 western states of the United States. Snow-cover and wildfire data were aggregated and normalized for each state, as well as for the entire western region. Mean annual snow-cover and wildfire extent values were determined for each geographic unit, and Z-score values were produced indicating departure from the mean for each year. For each of the 11 states and the region, as a whole, graphs were produced illustrating the relationships between snow-cover and wildfire patterns. No strong correlation was found for the entire western United States, nor did state aggregations show signs of consistent yearly correlation between measures of snow cover and wildfire. Nevertheless, a few states experienced above-average acreage burned totals following winters with above-average snow cover.