Spatial variability and trends in observed snow depth over North America

[1] This study uses a gridded dataset of daily U. S. and Canadian surface observations from 1960-2000 to study regional spatial and temporal variability and trends in snow depth across North America. Analysis shows minimal change in North American snow depth through January, with regions of decreasing snow depths beginning in late January. These regional decreases grow in intensity and extent through March and into April, implying an earlier onset of spring melt. The region showing the greatest decreases in snow depth occurs in central Canada, along a line from the Yukon Territory in northwestern Canada to the Great Lakes region. The regional decreases in spring snow depth across central Canada are likely a result of more rapid melt of shallower winter snowpacks, evident through shallower snow cover (2-10 cm) during May and October and a decrease in extent of deeper snowpacks (> 40 cm) through March and April.