Avalanche Forecast

Issued: Jan 31st, 2022 5:36PM

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

Lisa Paulson,

Email

15-35 cm of recent light snow is not bonding well to the underlying snow. Choose lower angle terrain for riding and carefully select climbs to manage the new problems.

Summary

Weather Forecast

As the Arctic air slides into the region for a short visit, temperatures will noticeably drop in the afternoon as the winds shift to light from the North. The coldest day will be Wednesday where morning temps will be in the -25 range with sunny skies and then warm through the day and into Thursday.

Snowpack Summary

15-35 cm in the last 24 hrs has created fresh windslabs and surface instabilities that are bonding poorly to the underlying surface of surface hoar/crusts/facets. Expect easy triggering of these soft slabs. It's unlikely to wake up the deep facets, but they continue to lurk 100-180 cm deep & could be triggered by cornice failures should they occur.

Avalanche Summary

New wind slabs were ski & explosive triggered in the immediate lees by the ski hill snow safety teams. In Yoho, numerous storm slabs observed/triggered in steep terrain. Over the past week there have been a few avalanche to sizes 3 on the persistent weak layer. All were triggered by large loads (cornice).

Confidence

Problems

Wind Slabs

An icon showing Wind Slabs

New windslabs have formed in the immediate lees of features and are up to 40 cm deep. This is different from the windslabs described in previous days.

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

An icon showing Storm Slabs

There is a touchy storm snow interface, down 15-35 cm, on surface hoar/crust/facets buried on Jan 30. Steep rolls with >20 cm of snow are most reactive, if they have not already slid.

  • Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Very Likely

Expected Size

1 - 1.5

Persistent Slabs

An icon showing Persistent Slabs

This problem represents both the Dec. 2nd crust/ facet layer (treeline and below) and the late December facet layer. Lots of variation in the sensitivity ranging from reactive sudden collapse to no results depending on location, aspect and elevation.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 1st, 2022 4:00PM