Avalanche Forecast

Issued: Jan 31st, 2022 4:00PM

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

Avalanche Canada astclair, Avalanche Canada

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Start with simple, well-supported terrain. Continually assess wind-drifted areas, and carefully monitor for surface hoar underneath the storm snow.

Summary

Confidence

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

Weather Forecast

Monday night: Mainly cloudy, moderate northwest winds, treeline low temperatures near -12 C, freezing level dropping to 100 m. 

Tuesday: Mostly clear, light northwest winds, treeline high temperatures near -11 C, freezing level rising to 400 m.

Wednesday: Cloudy, scattered flurries in the afternoon with up to 5 cm of snow, west winds increasing to moderate, treeline high temperatures near -8 C, freezing level near valley bottom.

Thursday: Cloudy, scattered flurries with up to 5 cm of snow, moderate west winds, treeline high temperatures rising to -4 C in the late afternoon, freezing level rising to 700 m. 

Avalanche Summary

Wind slabs and lingering storm slab avalanches may remain sensitive to human-triggering on Tuesday. Cornices could be reaching their breaking point and could act as triggers on slopes below. 

On Monday, operators reported numerous large (size 2-2.5) human and explosive-triggered avalanches breaking 20-50 cm deep in the recent storm snow. In a few areas, these slabs broke 70-100 cm deep. In the backcountry on Sunday, a group reported triggering a small (size 1.5) avalanche near Gin Peak. The avalanche was triggered remotely from below and broke 50 cm deep. 

Last week, explosive control work near Whistler produced a cornice fall that triggered a size 2.5 deep persistent slab on the weak faceted crystals above the early December crust. The slab broke 60-130cm deep. This indicates that while the weak layer is unlikely to be affected by skiers and riders, it is still triggerable by very large loads. 

Snowpack Summary

Over the weekend, the mountains picked up 30-50 cm of new snow. Strong to extreme southwest winds during the storm have since become moderate from the northwest and have redistributed the recent snow into wind slabs across a range of aspects at upper elevations. Monitor for changing slab conditions as you move into wind-exposed terrain. 

The recent snow is settling and stabilizing; however, there is lingering uncertainty as to whether a layer of surface hoar may sit above a crust. This layer is most likely to be preserved in sheltered areas at upper treeline elevations. If you are increasing your exposure to avalanche terrain, carefully evaluate the bond of the new snow to the crust. 

Below the storm snow, a thick melt freeze crust can be found on all aspects up to approximately 2200 m. It is possible to find another crust layer buried down 100-200 cm with facets above it from December. This layer is most prominent between 1700-2100 m and is currently classified as dormant; although large loads such as a cornice failure or avalanches in motion may still be able to trigger avalanches on this layer.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Extra caution is needed around cornices under the current conditions.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.

Problems

Wind Slabs

An icon showing Wind Slabs

30-50 cm of recent snow has been redistributed into wind slabs at upper elevations. Strong winds have shifted from the southwest to the northwest making it possible to trigger these wind slabs on a range of aspects. Cornices are large and looming and may trigger avalanches on slopes below.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Storm Slabs

An icon showing Storm Slabs

There is uncertainty surrounding the presence of surface hoar at the recent storm snow interface, particularly around treeline elevations. If you are increasing your exposure to avalanche terrain, carefully evaluate the bond of the new snow to the crust. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

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