Avalanche Forecast

Issued: Jan 26th, 2020 4:00PM

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

Avalanche Canada astclair, Avalanche Canada

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Triggering avalanches remains possible where winds have drifted the recent snow into slabs. Seek out sheltered slopes and monitor for these conditions if travelling in wind-exposed areas.

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Sunday night: Mostly cloudy with isolated flurries, light southwest winds gusting moderate, alpine temperature -3 C, freezing level around 1300 m.

Monday: Cloudy with periods of sun, isolated flurries, light southwest winds, alpine high temperature -3 C, freezing level around 1500 m.

Tuesday: Mix of sun and cloud, isolated flurries, light southwest winds, alpine high temperature -2 C, freezing level around 1500 m.

Wednesday: Mix of sun and cloud, moderate southwest winds, alpine high temperature -3 C, freezing level 1400 m.

Avalanche Summary

A recent natural, large (size 2.5) wind slab avalanche was reported on Saturday. 

On January 16th, a natural, size 2 wind slab stepped down to the deep persistent basal facets below a rock band, details here.

Snowpack Summary

Recent strong west winds have formed stiff wind slabs in exposed areas on leeward aspects at and above treeline. A crust can be found up to treeline and on solar aspects in the alpine due to recent daytime warming and sun exposure.

A well consolidated mid-pack overlies a generally weak basal snowpack. The bottom 10-20 cm of the snowpack consists of facets and deteriorating crusts. Although inherently weak, the benign weather pattern this week will likely promote a decreasing trend in reactivity for this avalanche problem. Areas that are most likely to harbor this problem are shallow, rocky start zones

Terrain and Travel

  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs

Strong southwest winds have blown recent snow into stiff wind slabs in lee features at alpine and treeline. Natural activity may have subsided but human triggering remains possible.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Mild temperatures are helping the basal weak layers to adjust and the snowpack to strengthen. Deep persistent slab avalanches on these layers are unlikely but may still be triggered from shallow snowpack areas near rocky outcroppings.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Jan 27th, 2020 5:00PM