Avalanche Forecast

Thursday night: Flurries, up to 5 cm new snow, moderate to strong westerly wind, alpine temperature near -10.

Friday: Mix of sun and cloud, moderate to strong northwest wind, alpine high -5, freezing level 1500 m.

Saturday: Mainly cloudy, moderate southwest wind, alpine high -7, freezing level valley bottom.

Sunday: Mix of sun and cloud, moderate northwest wind, alpine high -12, freezing level valley bottom.

There have been numerous natural, human and explosives triggered avalanches reported over the last couple of days, up to size 3.5. Most of these avalanches failed on the recently buried persistent weak layer. Many occurred at elevations around treeline where the layer exists as surface hoar.

It is notable that a size 3.5 was reported to have failed on a crust that was buried in early December. A smaller avalanche stepped down to this deeper layer, resulting in a very large and destructive avalanche.

20-40 cm of snow sits on a freezing rain crust in some parts of the region. It is not known how widespread this layer is, but it may have the potential to produce avalanches where it exists.

There is now about 50-80 cm of recent storm snow sitting above a persistent weak layer that consists of facets in some areas, a melt-freeze crust in many areas, on a sun crust on steep south-facing slopes, and large surface hoar in sheltered areas. This layer has been the most reactive at treeline and below treeline, where it exists as surface hoar.

There are potentially several more layers of surface hoar in the upper snowpack, with the most notable one down about 80-120 cm. This layer was buried in early January. 

A crust surrounded by weak faceted grains is buried deep within the snowpack. It may be possible to trigger this layers with a large load.

• Be aware of the potential for large avalanches due to the presence of buried surface hoar.
• Keep in mind that human triggering potential persists as natural avalanching tapers off.
• Avoid freshly wind loaded terrain features.