Avalanche Forecast
Issued: Dec 10th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
The high alpine holds good snow for those willing to work for it. Travel conditions may be difficult with minimal snow coverage at lower elevations and where the crust is punchy and unsupportive.
Summary
Confidence
Weather Forecast
Thursday night: Isolated flurries, light to moderate southwest ridgetop wind, Freezing level 500 m.
Friday: Isolated flurries with sunny breaks, light north ridgetop wind / alpine high -7C, freezing level 700 m.
Saturday: Sunny, light southwest ridgetop wind, alpine high temperature -5C, freezing level 500 m.
Sunday: Sun and cloud, moderate southwest ridgetop wind, alpine high -7C, freezing level 500 m.
Avalanche Summary
On Wednesday, natural avalanche activity was limited to loose dry to size 1.5.
A widespread natural cycle occurred during the storm Monday night through Tuesday, storm slabs size 2-3 and loose wet size 1-2.
On Tuesday December 1, a large size 3 natural avalanche was observed on a NE aspect at 2400 m in the Duffy area. It was reported as a cornice failure triggering the slope below and appeared to have slid on the early November crust near the base of the snowpack.
Have you been out and about in the mountains? If so please submit your observations to the Mountain Information Network (MIN). It doesn't have to be technical - photos are especially helpful! Thank you so much for all the great MINs submitted so far!
Snowpack Summary
- In the south, 10-15 cm of dry surface snow bonds to the underlying crust formed earlier this week when 25 mm of rain soaked the upper snowpack at all elevations. We've got our eye on a couple of crusts in the upper to mid snowpack that are producing moderate to hard snowpack test results. Treeline snowpack depth sits around 80-130 cm.
- In the north, around 30 cm of recent snow sits over a thin zipper crust above 2300 m, snow tapering with elevation. Between 1600 and 2000 m, the crust is punchy and unsupportive. In the lower snowpack, a crust/facet layer sits near the ground. The most recent avalanche observed on this layer was on December 1st, while recent snowpack tests in the Cayoosh zone found this layer down 60 cm and unreactive. We have a lot of uncertainty on the reactivity of this layer so we're keeping it on our radar.
Terrain and Travel
- A crust on the surface will help bind the snow together, but may make for tough travel conditions.
- Be alert to conditions that change with elevation.
- Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
Problems
Storm Slabs
Keep a look out for lingering storm slabs around steep rolls and extreme terrain.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
In the north of the region (e.g., Duffey Lake), a weak layer of sugary faceted grains around a hard melt-freeze crust sits near the base of the snowpack. There is a lot of uncertainty on the reactivity of this layer - we're keeping it on our radar because we don't have enough information. Be wary of overhead hazards, a large impact (like a cornice failure - see avalanche summary) could trigger the slope below. Keep in mind if this layer is triggered, it will likely produce large avalanches.
This problem does not exist in the south of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 11th, 2020 4:00PM
