Avalanche Forecast
Issued: Dec 15th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
TRettie,
Avalanche Canada
Use extra caution near ridgelines and "thick to thin" areas where the likelihood of triggering avalanches will be greater.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
Wednesday night: some light flurries with moderate Southwest winds. Low of -11 at 1500m.
Thursday: light Southwest winds in the morning with some flurries bringing up to 5cm of new snow. Winds will shift to moderate from the Northwest in the alpine. High of -9 at 1500m.
Friday: High of -13 at 1500m. Moderate Northwest winds in the morning shifting to Southwest in the afternoon. Some light flurries in the afternoon.
Saturday: A storm arrives bringing up to 20cm of new snow with strong Southwest winds. High of -10 at 1500m.
Avalanche Summary
On Tuesday explosives triggered numerous storm slab avalanches up to size 1.5 on North and East aspects in terrain between 2200 and 2350m.
Snowpack Summary
10 to 30cm of low density snow fell Tuesday morning with the largest amounts in the Selkirks. This overlies old storm snow that was redistributed by moderate Southeast winds.
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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 growing above it. The facets above the crust are most prominent at upper 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.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
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
Expected Size
Persistent Slabs
50 to 100cm of snow sits above the early December facet crust combo. The faceting above this crust is most prominent at the upper treeline. Few avalanches have been reported on this layer but they have been large. Use extra caution in "thick to thin" areas where sensitivity to triggering this layer could be greater.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 16th, 2021 4:00PM
