Avalanche Forecast
Issued: Dec 19th, 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.
jleblanc,
Avalanche Canada
Don't let the desire for deep powder pull you into high consequence terrain. Keep making conservative choices, especially at treeline where a persistent slab problem still exists.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
An Arctic ridge of high pressure will continue to build into the Interior, bringing clear skies and cold conditions with outflow winds through Monday.
SUNDAY NIGHT: Clearing skies / Light north wind / Low of -19
MONDAY: Sunny / Light west wind / High of -15
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TUESDAY: Increasing cloudiness / Moderate to strong west wind / High of -13
WEDNESDAY: Snow 5-15 cm / Strong southwest wind / High -10
More details can be found on the Mountain Weather Forecast.
Avalanche Summary
A widespread natural cycle of storm slabs was observed at all elevations on most steep features during Saturday's storm. Poor visibility restricted avalanche observations during most of the storm.Â
On Tuesday, a skier triggered size 1.5 was reported on a North aspect at 2200m. This avalanche occurred on the early December crust/facet combo. The avalanche was triggered by the sixth skier to enter the slope.
If you go out, make sure to report any observations on the Mountain Information Network. Â
Snowpack Summary
The storm brought around 20-35 cm of new snow in the region, favoring the northeast areas with amounts up to 45 cm. Significant strong southerly winds have formed touchy storm slabs, especially in wind-affected terrain. Many sluffs were triggered by skiers on steep slopes.
Below the new snow, the defining feature of the snowpack is a widespread crust that reaches as high as 2400 m and now sits 50-120 cm below the surface.Â
In some places, overlying snow is well-bonded to the crust but in others, weak faceted grains have been observed above it. The faceting is most prominent at treeline where the crust is thinner.Â
The recent snow has increased the likelihood of triggering this layer.
Terrain and Travel
- Don't let the desire for deep powder pull you into high consequence terrain.
- Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
Problems
Wind Slabs
20-35 cm + of low-density snow will be available for wind transport Monday. Northwest circulation will also bring cold temperatures and different wind patterns. Touchy wind slabs will build throughout the day on alpine slopes that have not seen wind slabs during the previous storm.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 60-150 cm near a crust layer that formed in early December. This persistent slab problem has recently been most reactive at TREELINE elevations and is possible to human trigger on some slopes. Avoid likely trigger spots such as steep, convex slopes, with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 20th, 2021 4:00PM
