Avalanche Forecast

Issued: Dec 4th, 2017 4:10PM

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

Avalanche Canada cgarritty, Avalanche Canada

Lingering wind slab and persistent slab problems will keep avalanche danger in a holding pattern for one more day. Warm temperatures are set to undermine stability in the midweek.

Summary

Confidence

Moderate -

Weather Forecast

Tuesday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate west winds. Weak alpine temperature inversion bringing alpine temperatures to around -2.Wednesday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light southwest winds. Freezing level rising to over 3000 metres with alpine temperatures around +5. Cooler temperatures at valley bottom due to temperature inversion.Thursday: Mainly sunny with some valley cloud due to lingering temperature inversion. Light to moderate southwest winds. Freezing level to over 3000 metres with alpine temperatures around +5. Cooler temperatures at valley bottom.

Avalanche Summary

No recent avalanche activity has been reported. Stiff wind slabs may exist at treeline and in the alpine on leeward slopes and cross-loaded features. If triggered, these could step down to trigger deeper weak layers and initiate large avalanches. The last significant avalanche observation was submitted on November 28th from Skilokis Creek. Here, a size 2.5 persistent slab was triggered from 150 m away. This problem will likely linger. Check out the Mountain Information Network for more details. Give info, get info.

Snowpack Summary

Average snowpack depths now total 80-140 cm at treeline elevations and up to 160 cm in the alpine. Alpine snow surfaces are likely wind affected. Below the surface, approximately 30-50 cm of recent snow now overlies two crusts that were buried near the end of November. These crusts are widespread and extend well into the alpine. Recent snowpack tests have shown sudden results at these crust interfaces. Below these crusts, we have a well settled midpack overlying the late October crust near the base of the snowpack. This late October "crust/facet combo" is widespread and has been reactive to rider and remote triggers.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The late October crust lies near the base of the snowpack with a thin layer of weak, sugary snow above it. This layer has recently produced very large avalanches with both rider triggers as well as remote triggers.
Be cautious in shallow snowpack areas where triggering a deeper layer may be easier.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

An icon showing Wind Slabs
Recent snow and wind have formed touchy wind slabs. Expect these slabs to be more pronounced at higher elevations and on leeward aspects. Signs of wind affected snow include whumpfing and cracking.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Increase your caution around convexities and areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 5th, 2017 2:00PM