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.
astclair,
Avalanche Canada
Watch for changing conditions in wind-exposed areas. If winds pick up, fresh reactive wind slabs may form. Avoid slopes where a slab is stiffening above a persistent weak layer.
Summary
Confidence
Weather Forecast
Wednesday night: Partly cloudy, a trace of snow possible, light southwest winds, alpine temperatures around -12 C.
Thursday: Partly cloudy, 0-2 cm of snow expected, light southwest winds trending to strong northwest at higher elevations in the afternoon, alpine temperatures cooling from -12 C to around -14 C.
Friday: Clear with a few clouds, no new snow expected, light west winds, trending to moderate northwest in the alpine, alpine temperatures around -11 C.
Saturday: Increasing clouds, a trace of snow expected, moderate southwest winds with strong gusts in the alpine, alpine high temperatures around -8 C.
Avalanche Summary
On Wednesday, avalanche control triggered a very large (size 3) avalanche on a northwest aspect around 2050 m that released on the early December weak layer. On Tuesday, a large (size 2) avalanche was remotely-triggered on this same layer by a skier. This occurred on a west aspect near 2100 m and broke 100 cm deep.
Earlier in the week, avalanche control in the north of the region produced small avalanches in the storm snow.
On Sunday, a small, skier remote triggered avalanche was reported that failed on a reloaded bed surface near the base of the snowpack on a north aspect in the alpine. There were other deep failures reported in this region about a week ago. This information is spotty, but it is consistent with a deep persistent problem that may be difficult to trigger. We're not done worrying about this one yet.
Snowpack Summary
Up to 20 cm of snow has accumulated since Monday with periods of moderate wind at upper elevations. With snow available for transport, be aware of the potential for intermittent wind to form reactive slabs in lee terrain features.
Below this layer, consolidated snow from the previous weekend storm sits over a substantial crust that formed in early December. This crust is 10-40 cm thick and can be found down 40-80 cm. It is present across aspects below 2300m. A thin layer of weak facets (sugary snow) can found above this crust that has demonstrated reactivity in snowpack tests and recent avalanche activity.
A late October facet/crust layer of concern sits at the bottom of the snowpack above 1900m. Although this layer has been trending less reactive, it remains on our radar.
The snowpack depth at treeline is around 115-200 cm. The deepest snowpack can be found near the Bugaboos.
Terrain and Travel
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Use conservative route selection and resist venturing out into complex terrain.
Problems
Wind Slabs
Be alert to changing conditions. Winds are forecast to shift to the northwest and increase at upper elevations, which may form fresh wind slabs that are reactive to human triggering. Previous moderate to strong southwest to southeast winds built slabs in leeward terrain and may also remain possible to trigger.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 40-70 cm over a crust that formed in early December. As the recent snow is settling and stiffening above, this layer is beginning to produce avalanches and warrants conservative terrain selection.
At the base of the snowpack above 2200 m, a layer of depth hoar lingers. Avalanches-in-motion have the potential to step down to this layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 16th, 2021 4:00PM
