Avalanche Forecast
Issued: Dec 25th, 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.
ahanna,
Avalanche Canada
Be aware of changing avalanche conditions as you gain elevation. Recent snow sits over a weak layer in the trees and wind slabs have been reactive up high. As temperatures drop, make sure to keep an eye on the daylight and leave plenty of time to get home safely.
Summary
Confidence
Weather Forecast
Flurries tapering and cold temperatures setting in.
Saturday night: Cloudy with scattered flurries, 5 cm. Light to moderate southwest wind. Treeline temperature around -14 C.
Sunday: Mostly cloudy with scattered flurries, 5 cm. Light to moderate southwest wind. Treeline temperature around -18 C.
Monday: Mix of sun and cloud. Light variable wind. Treeline temperature around -20 C.
Tuesday: Mix of sun and cloud. Light variable wind. Treeline temperature around -24 C.
Avalanche Summary
On Friday, size 1 wind and storm slab avalanches were reactive to skiers and explosives, additionally a couple of natural size 1 wind slab avalanches were reported on a northeast aspect at 2450m.
Explosives Wednesday, Thursday, and Friday continued to trigger size 1-2 persistent slab avalanches at treeline elevations near Invermere, these failed on the crust-facet layer 40-70 cm deep.
On Wednesday, a few small (up to size 1) natural and human-triggered wind slab avalanches were reported.
Snowpack Summary
20-60 cm of recent snow has seen some redistribution at upper elevations, forming deep, soft deposits in leeward terrain features. The recent snow may sit over a layer of weak surface hoar crystals at treeline and below.
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.
Terrain and Travel
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Problems
Wind Slabs
Reactive slabs continue to linger, especially where they sit above a surface hoar interface. Leeward wind-loaded slopes may host thicker and stiffer slabs. Be mindful of loose-dry sluffing in steeper wind-sheltered terrain.
Aspects: All aspects.
Elevations: All elevations.
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.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 26th, 2021 4:00PM
