It has been a phenomenal winter in western Canada, with continual storms and fresh powder. However, the region experienced a week in mid-February of clear, cool weather without significant winds. This led to the growth of 5 mm to 15 mm surface hoar on many aspects and elevations, upon which subsequent snowfall has been stacking. This persistent weak layer, now buried 30 cm to 90 cm deep, has become problematic in the Columbia Mountains up to the Cariboos and western Purcells, and also in the South and Northwest Coastal regions.

If you have plans to ski tour in B.C. in the coming weeks, read Avalanche Canada’s recent blog, House of Cards, to understand the problem, its distribution, and their travel advice. They advise that it might takes weeks for the layer to become less problematic and that “diligent terrain travel will be crucial until it is clear that this problem has been put to rest.”

For an in-depth look at how surface hoar forms and how it affects the snowpack, read this article on avalanche.org’s Avalanche Encyclopedia.