Avalanche Forecast

Issued: Dec 16th, 2021 4:00PM

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

Avalanche Canada TRettie, Avalanche Canada

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We are reaching a tipping point where triggering large, destructive avalanches will become more likely . Where exactly these large avalanches can be triggered will be hard to predict. Read the forecaster's blog to learn more.

Summary

Confidence

Low - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

Thursday night: Some light flurries with light to moderate Northwest winds in the alpine. Low of -15 at 1500m.

Friday: High of -13 at 1500m. Moderate Northwest winds in the morning shifting to Southwest in the afternoon. Sunny and no new snow expected.

Saturday: A storm arrives bringing up to 40cm of new snow with the highest snowfall in the Southwest corner of the forecast region. Winds will be strong from the Southwest. High of -10 at 1500m.

Sunday: High of -9 at 1500m. light snow in the morning. Strong Southwest winds in the morning becoming light West in the afternoon.

Avalanche Summary

One natural size 2.5 was observed in the Monashees on Wednesday on a West aspect at 2150m. This avalanche failed on the early December facet/crust combo. The crown was one meter deep, a good indicator of the high consequences of triggering this layer.

Snowpack Summary

Up to 10cm of low density snow fell over the region Thursday morning. This overlies a variety of surfaces including old wind slab and storm snow. 

The defining feature of the snowpack is a widespread crust that reaches as high as 2200 m and now sits 50-100 cm below the surface. In many places overlying snow is well-bonded to the crust but in others weak faceted grains have been observed above it. The facets above the crust are most prominent at treeline where the crust is thinner.

Average snowpack depth at treeline is 250cm.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Persistent Slabs

An icon showing Persistent Slabs

The faceting above this crust is most prominent at the treeline. Use extra caution in "thick to thin" areas and on solar aspects where sensitivity to triggering this layer could be greater.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

An icon showing Wind Slabs

Skier triggerable wind slabs have still been observed on wind loaded slopes in the treeline and alpine.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

1 - 2

Valid until: Dec 17th, 2021 4:00PM