Avalanche Forecast

Issued: Jan 22nd, 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 jfloyer, Avalanche Canada

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Staying safe involves selecting sheltered terrain away from wind-affected snow. As a bonus, this is also where the best riding will be found.

Summary

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Wednesday night: Flurries. Moderate southwesterly winds. Freezing level around 1000 m.

Thursday: Flurries. Strong southwesterly winds. Freezing level rising to around 1500 m in the afternoon.

Friday: Around 4 cm new snow. Moderate southwesterly winds. Freezing level around 1800 m.

Saturday: Around 4 cm new snow. Moderate southwesterly winds. Freezing level around 1600 m.

Avalanche Summary

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 terrain at treeline and alpine locations. A crust can be found at lower elevations and on solar aspects 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. There is potential for this deep persistent layer to reawaken in the warm alpine temperatures later in the week.

Terrain and Travel

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • 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.
  • Extra caution for areas experiencing rapidly warming temperatures for the first time.

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. Human triggering of wind slabs is possible.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

As temperatures trend warmer and freezing levels rise, there is potential for the deep basal weak layers to become active. Deep persistent slab avalanches on these layers are most likely to be triggered from shallow snowpack areas near rocky outcroppings.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 23rd, 2020 5:00PM

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