Avalanche Forecast

Issued: Mar 7th, 2021 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Cornices and Loose Wet.

Avalanche Canada astclair, Avalanche Canada

Sunny skies and rising temperatures may initiate wet loose activity on lower elevation and/or sun-exposed slopes. Steer clear of cornices and wind-drifted areas as they have the potential to produce large avalanches. 

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength. Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

Dry conditions for the next few days

Sunday night: Partly cloudy, isolated flurries with trace accumulations, light southwest winds, freezing level dropping to valley bottom.

Monday: Mainly sunny, light south winds, freezing level rising to 1400 m and dropping to valley bottom overnight.

Tuesday: Mix of sun and cloud, light southwest winds, freezing level rising to 1300 m and dropping to valley bottom overnight.

Wednesday: Partly cloudy, scattered flurries with trace accumulations, moderate northwest winds, freezing level rising to 1000 m. 

Avalanche Summary

In the north of the region, reports indicate that an avalanche cycle occurred during the storm on Friday, where large (size 2.5) avalanches released naturally on a variety of aspects and elevations. Check out these MIN reports (here and here) from slopes near Chief Pascall. 

Last week, observers near Duffey Lake reported a large (size 2.5) avalanche on a north aspect at 1750 m that was thought to have released 1 m deep on a persistent weak layer. Additionally, a size 1.5 skier accidental was reported on a northwest aspect in the alpine, which was also near Duffey Lake and also thought to have failed on a thin persistent weak layer of facets. 

In the south of the region, there have been numerous reports of large (size 2-3) natural glide slab avalanches over the past week. Glide slabs are most likely in areas of smooth ground cover such as rock slabs and can be large, involving the full depth of the snowpack. Carefully consider your access/egress routes where they cross under large paths. 

Snowpack Summary

In the north of the region, 30-50 cm of new snow over the weekend has been redistributed by strong south winds into wind slabs on leeward slopes that may be likely to trigger. Massive cornices exist on ridgelines, which can act as triggers on slopes below.  

Deeper in the snowpack, a persistent weak layer of facets can be found from mid-February on north aspects near treeline that demonstrated reactivity where it separates wind-stiffened snow above and below. There is some lingering uncertainty about whether this problem remains reactive in isolated areas. The lower snowpack is generally well settled and strong.

The south of the region received only a trace of new snow over the weekend with moderate wind. The danger ratings are Moderate, Low, Low, with a concern for small wind slabs. The snowpack is generally well consolidated with no concerns of buried weak layers but recent notable glide avalanche activity.

Terrain and Travel

  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Cornice failure may trigger large avalanches.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.

Problems

Wind Slabs

An icon showing Wind Slabs

In the north of the region, 30-50 cm of snow has been redistributed by strong south winds into reactive wind slabs on lee features. Watch for cracking, changes in snow stiffness, and the pattern of wind-drifting in the terrain where you are traveling. Triggering large wind slabs on specific features remains likely on Monday. 

Aspects: North, North East, East, South East, West, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Cornices

An icon showing Cornices

In the north of the region, cornices have seen substantial growth since the last storm, and they may release naturally with the impact of solar radiation. Cornice falls can act as triggers on slopes below. 

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

An icon showing Loose Wet

Wet loose avalanches may release naturally on low elevation or steep sun-exposed slopes. A wet snow surface, pinwheeling or loose wet point releases out of the rocks are good indicators that it is time to back off. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 8th, 2021 4:00PM