We continued to have avalanches this past week failing in the persistent weak layer of faceted snow down near the ground. This has included control work at resorts in unopened terrain, as well as riders remotely-triggering slides from a distance. These slides are 2-3' deep and up to 200' wide.

This weak snow can be found on mid and upper elevation slopes facing northwest through north and east. Over the past 24 hours, we have stressed this weak layer with an additional 12-18" of snow containing nearly 2" of water as well as strong winds depositing wind-drifted snow on these slopes.

Click on the button below for more details on how this layer formed and where you can find it.

It's quite simple - stay off of and out from underneath slopes steeper than 30 degrees on slopes facing northwest through north and east. Avalanches can be triggered from below, and the dense snow and wind slabs can allow a rider to get well onto a slope before it avalanches. Any avalanches on these slopes may be 3-4' deep and several hundred feet wide.

Strong westerly winds at the mid and upper elevations will create dense wind slabs. Although these fresh drifts will mostly be found on leeward aspects facing north through southeast, strong winds can often be channeled through terrain features and you may find wind drifts on any aspect. Cornices may be sensitive and can break back much further than expected. Avoid being on any slopes steeper than 30 degrees that are wind-loaded. The photo below shows cracking in wind-drifted snow - the best evidence of sensitive wind drifts and cornices. (Mark White)

You can expect to find sensitive storm snow at the mid and upper elevations, especially during any period of higher precipitation. Storm snow instabilities typically diminish quickly (ie a few hours), however the existing snowpack that the storm snow landed upon had developed weaknesses at the surface, including surface hoar and near-surface facets, and this may allow the storm snow to remain sensitive much longer. Yesterday, a long-time observer was finding a poor bond with the old snow surface in Millcreek (observation) and in upper Little Cottonwood I was finding preserved near-surface facets underneath the few inches of storm snow that had fallen (observation). We will need additional field work to determine if these buried weak layers are reactive and how widespread they have been preserved.