Avalanche Forecast
Issued: Dec 27th, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
JSmith,
Avalanche Canada
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Keep in mind that cold temperatures significantly increase the consequence of even minor injuries in the backcountry.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
MONDAY NIGHT: Partly cloudy / Light west wind / Low of -25
TUESDAY: Mostly cloudy / Light northwest wind / High of -19
WEDNESDAY: Sunny / Light northwest wind / High of -21
THURSDAY: Mostly cloudy / Light to moderate northwest wind / High of -20
Avalanche Summary
Numerous skier triggered size 1 dry loose avalanches were reported on Sunday. Expect dry loose avalanches (sluffing) running far and fast in steep terrain.
Explosive work near Invermere continues to produce avalanches on the reloaded bed surface of the crust-facet layer formed in early December, found 40-70 cm deep in that area.
Snowpack Summary
Variable wind direction has resulted in redistribution of 20-60 cm of recent snow at upper elevations. The recent snow may sit over a layer of weak surface hoar crystals at treeline and below. Expect dry loose avalanches (sluffing) running far and fast in steep terrain.
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The upper snowpack overlies a substantial crust from early December. This crust is approximately 60-120 cm below the surface, 10-30 cm thick on average, and is present across all aspects to at least 2300 m. A layer of weak facets (sugary snow) has been reported above this crust. Snowpack tests are generally showing hard results on this interface.
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 120-250 cm. The deepest snowpack can be found in the southern half of the region.Â
Terrain and Travel
- Use small low consequence slopes to test the bond of the new snow.
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- If triggered, loose dry avalanches may step down to deeper layers resulting in large avalanches.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
Problems
Wind Slabs
Wind slabs likely remain reactive to human triggers, especially where they sit above a surface hoar interface. Watch for cracking or visibly loaded pockets of snow in leeward terrain features like below ridge crests and roll-overs on all aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 40-120 cm over a crust that formed in early December. This layer has shown some reactivity in snowpack and explosives tests. New snow or smaller avalanches may add enough stress to trigger a persistent slab.
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.
While the weight of a person is less likely to trigger layers of this depth, it still may be possible where the snowpack transitions from thick to thin, such as near rocky outcroppings.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 28th, 2021 3:00PM
