Avalanche Forecast

Moderate - Wind effect is extremely variable

Tuesday night: 10-15cm of new snow / Strong westerly winds / Alpine temperatures of about -13Wednesday: Light flurries / Strong westerly winds / Alpine temperatures of about -13Thursday: 10-15cm of new snow / Strong southerly winds / Alpine temperatures of about -10Friday: Light flurries / Moderate westerly winds / Alpine temperatures of about -12

A Mountain Information Network post from the Adamant Range on the eastern side of the Selkirks indicated several avalanches failing on the mid-December weak layer throughout last week. The avalanches were in the size 1-2.5 range and were failing under light loads, in some cases naturally or remotely. On Christmas Day, there was another MIN post where a size 2 slab avalanche was triggered on an alpine slope on Video Peak in Glacier National Park. The avalanche, which was thought to have failed on the mid-December layer, was triggered remotely from a distance of 30 metres. Both of these avalanches point to the potentially touchy nature of the mid-December layer in some areas. No new avalanches were reported at the time of publishing this bulletin on Tuesday. I'm sure there was some natural wind slab activity in response to new snow and wind on Monday night. Continued strong ridgetop winds should promote ongoing wind slab activity. For the short term, I also expect loose dry avalanches to be triggered easily in steep sheltered terrain.

Between 20 and 65 cm of new snow fell on Monday night with the highest accumulations occurring in the Monashees. In higher elevation terrain where the winds were stronger, these accumulations have likely been shifted into much deeper and potentially reactive wind slabs. In areas sheltered from the wind, the new snow is mostly loose and unconsolidated. 50-90cm below the surface you'll find the mid-December interface which consists of wind affected snow, faceted (sugary) crystals, and/or surface hoar crystals. Recent tests suggest the the new snow is well bonded to the interface in most areas. However, this layer is still reactive in some snowpack tests and should be investigated before pushing into steeper terrain. Limited observations suggest this layer has been especially touchy on the eastern side of the Selkirks. The thick mid-November crust layer typically sits 1-2 m down in the snowpack. Recent test results on this layer suggest it is generally well bonded to the adjacent snow with the possible exception of shallow snowpack areas. This layer is considered dormant at this time but remains an isolated concern that we will likely be tracking through much of the season.