A Climatology of Blowing Snow in Canada and the United States

Blowing snow (BS) can make many forms of travel dangerous and investigating where BS occurs frequently is important to understanding the linkage between hazardous conditions and impacts on travel. This unique research is one of only a few studies to use observations to identify occurrences of BS and investigates the spatiotemporal variations of observed blowing snow hours and associated conditions during an extended time period over a large continental region. The study uses surface hourly observations from 133 stations across Canada and the United States during the 40 cold seasons (October – April) of 1979/80 to 2018/19. The Canadian Arctic region has recorded the greatest number of BS hours over the 40 cold seasons. BS is most active during the month of January with a seasonal peak in the number of BS hours for most locations, as well as a regional equatorward expansion in locations experiencing hours with BS. The least active month of the cold season was October, with most BS hours confined to Northern Canada. During the 40 cold seasons, BS hours have increased with time in most of Canada while decreasing across the United States, including Alaska. Observations of surface wind speed and air temperature were compared to the BS threshold wind speed derived from an empirical model. The average observed wind speed during BS hours across western and central Canada was found to be slower than the predicted threshold necessary. The average observed wind speed during BS hours in many regions across the United States, especially the Central Plains, and eastern Canada was found to be faster than the predicted threshold.