The temporal variability of USA snowfall is investigated for the period 1945-1946 through to 1984-1985 using linear trend and principal components analyses. The results of the linear trend analysis indicate that two regions of the USA evidence significant changes in monthly snowfall over the period. These areas include the Great Lakes/upper mid-west and high plains regions of the USA. In the Great Lakes/upper mid-west sector, positive linear trends are found in monthly snowfall totals for the mid-winter months (December, January, February). For the high plains region, positive linear trends are found for the month of December. Principal components analysis (PCA) is used with seasonal snowfall data in order to better understand the spatial and temporal nature of seasonal snowfall variations across the USA. The PCA isolates six spatially coherent regions in which seasonal snowfall varied similarly over the 40-year period. Only one of these regions, centred on the Great Lakes and upper mid-west, displays any long-term change in seasonal snowfall, a positive trend during the period 1945-1946 through to 1984-1985. These results are discussed in the context of man-induced and natural environmental changes.
