Avalanche Forecast

Issued: Dec 10th, 2019 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Persistent Slabs.

Avalanche Canada ahanna, Avalanche Canada

Email

Avalanche activity related to last week's storm has slowed down but several buried weak layers remain active. Use caution when pushing out into more complex terrain.

Summary

Confidence

Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Tuesday Night: Cloudy with isolated flurries, alpine low -9, moderate southwest wind.

Wednesday: Mix of sun and cloud with isolated flurries in parts of the region, alpine temperature -6, moderate southwest wind.

Thursday: Cloudy with flurries concentrated in the south of the region, accumulating 5-10 cm there with less in the north. Alpine temperature -5, moderate southwest wind.

Friday: Mainly cloudy with isolated flurries, alpine temperature -6, moderate southwest wind.

Avalanche Summary

The natural avalanche cycle that coincided with snowfall late last week has likely slowed down but it is important to keep in mind the potential for large, deep avalanches. Many of the reported avalanches in the previous storm cycle released on the weak layer buried in late November. As recently as Monday, up to size 2.5 avalanches have been observed, one of which released on the early season facet layer over glacial ice high in the alpine. Settlements and whumpfing, likely also on these basal facets, have been reported below treeline in response to skier traffic.

Snowpack Summary

150-250 cm of snow sits in the alpine in the central parts of the region. At the surface, a thin layer of moist snow or crust may be found on steep south-facing aspects. Last week's storm snow, 40-80 cm which constitutes the upper snowpack, continues to settle and gain density in the relatively warm alpine temperatures. The primary layers of concern are a couple of weak layers in the mid snowpack (60-120 cm below the surface), formed in late November and early December which can be found most notably at treeline, and may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. A variety of facet/crust layers from late October are buried near the bottom of the snowpack.

Problems

Persistent Slabs

An icon showing Persistent Slabs

A couple of weak layers formed in late November and early December, sitting 60-120 cm below the surface, may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. They can most likely be found in areas sheltered from the wind, but open to a view of the sky, such as near treeline.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Dec 11th, 2019 5:00PM