Avalanche Forecast
Issued: Dec 15th, 2022 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
Watch for fresh wind slabs forming on atypical aspects at ridgetop as upper level wind picks up from the northwest.
We have uncertainty around the reactivity of a buried weak layer that produced large rider-triggered avalanches last weekend. Read our latest blog for advice on how to manage a persistent slab problem.
Summary
Confidence
Avalanche Summary
Earlier this week, avalanche observations were mostly limited to small, explosive-triggered wind slabs.
Last weekend, there were several alarming reports of large (size 2-3) persistent slab avalanches. They were remotely triggered by skiers or snowmobiles at treeline elevations. Check out these MIN reports here and here. A huge thank you to the groups who shared their observations to the Mountain Information Network!
Snowpack Summary
A thin surface crust may be found on steep south aspects. 5-10 cm of recent snow rests over a layer of surface hoar at treeline and below. Near ridgetop, the recent snow is likely being reverse-loaded into atypical terrain features as upper level northwest winds pick up on Friday.
A well settled upper snowpack may overlie a layer of surface hoar formed in early December, now buried 30-50 cm deep.
A concerning weak layer consisting of facets and surface hoar formed in November is now buried 80-90 cm deep. At the bottom of the snowpack, a thick crust sits on the ground.
At treeline, snowpack depths vary from 120 to 200 cm.
Weather Summary
Thursday night
Partly cloudy. Ridgetop wind light to moderate west. Alpine low -14 C.
Friday
Mix of sun and cloud. Ridgetop wind moderate northwest. Alpine high -11 C.
Saturday
Around 5 cm new snow. Light southwest wind. Alpine high -9 C.
Sunday
Mix of sun and cloud with isolated flurries. Light to moderate southwest wind. Alpine high -20 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- 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.
- Avoid open slopes and convex rolls at and below treeline where weak layers may be preserved.
- In times of uncertainty conservative terrain choices are our best defense.
Problems
Wind Slabs
As ridgetop winds pick up from the northwest, watch for fresh wind slabs forming in atypical terrain features due to reverse-loading.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
A layer of surface hoar buried 30-50 cm deep has shown propagation in recent snowpack tests.
Layers of surface hoar and facets, buried 80-90 cm deep, were reactive to human triggers at treeline elevations last weekend.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 16th, 2022 4:00PM
