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Avalanche Forecast

Dec 13th, 2021–Dec 14th, 2021
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Vancouver Island.

Shifting winds continue to form fresh wind slabs that are possible to human trigger. Pay attention to changing conditions with elevation/aspect and avoid slopes that have been freshly wind-loaded.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

MONDAY NIGHT: Clearing skies / Light, northerly winds / Low of -7 C / Freezing level 500 m.

TUESDAY: Mostly sunny / Light, northwesterly winds / High of -1 C / Freezing level 600 m.

WEDNESDAY: Cloudy with flurries; 5-10 cm. / Strong, southerly winds / High of -1 C / Freezing level 600 m.

THURSDAY: Mix of sun and cloud / Moderate, northwesterly winds / High of 0 C / Freezing level 700 m.

Avalanche Summary

On Saturday, there were reports of numerous small (size 1-1.5) avalanches releasing 30-70 cm deep in the storm snow across a variety of aspects. See this MIN report from the Mt. Washington area for a helpful visual.

Snowpack Summary

An impressive storm over the weekend brought 50-90 cm of snow to the mountains. A gradual rise in temperature during the storm formed a crust layer that can be found in areas up to 1400 m. An additional 20-50 cm of snow has accumulated since temperatures cooled. 

Strong southerly winds have had an ample supply of snow to drift into wind slabs at upper elevations. It remains possible to trigger these wind slabs in lee terrain features, such as down-wind of ridges and roll-overs.

Monitor for changing conditions as you move into wind-exposed terrain and pay attention to cracking or hollow sounds.

Below the early December crust layers, the snowpack is generally well-settled. With this storm event, a greater number of areas below treeline are exceeding threshold snow depths for avalanches. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of highly variable recent wind loading patterns.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.

Avalanche Problems

Wind Slabs

Strong southerly winds and recent snow have formed wind slabs in lee terrain features at upper elevations that may remain possible to human trigger. Shifting winds overnight on Monday may form fresh wind slabs that are more sensitive to triggering.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2