Avalanche Forecast

Issued: Jan 25th, 2020 4:30PM

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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Areas where you can trigger an avalanche on Sunday are specific to where the wind has drifted the recent snow at higher elevations. Stay alert and monitor for these conditions if travelling in these areas.

Summary

Confidence

Moderate - Confidence is due to a stable weather pattern; little change is expected for several days.

Weather Forecast

Saturday night: Mostly cloudy, light southwest winds, alpine temperature -6 C, freezing level dropping to valley bottom.

Sunday: Mostly cloudy with isolated flurries, light southwest winds gusting moderate, alpine high temperature -3 C, freezing level around 1500 m.

Monday: Cloudy with periods of sun, isolated flurries, moderate southwest winds, alpine high temperature -2 C, freezing level around 1500 m.

Tuesday: Mix of sun and cloud, light southwest winds, alpine high temperature -2 C, freezing level around 1400 m.

Avalanche Summary

No recent avalanches have been reported. On Monday we received reports of natural and explosive triggered wind slab avalanches size 1.5-2.

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 westerly 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-snowpack 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.

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 southwesterly 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

Unlikely - Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

We suspect that mild temperatures are gradually helping the basal weak layers to bond 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 26th, 2020 5:00PM