Avalanche Forecast
Issued: Dec 4th, 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.
zryan,
Avalanche Canada
Diligently watch for changing conditions throughout the day. Increasing winds may form fresh, reactive wind slabs in the alpine and treeline.
Small avalanches have the potential to trigger deeper weak layers. Take a cautious approach to risk management and assess conditions as you travel.
Summary
Confidence
Avalanche Summary
On Saturday, a small (size 1) skier triggered persistent slab avalanche occurred on a northwest aspect at treeline. A larger (size 2) natural slab avalanche was also observed from a distance on an east-facing alpine slope.
Last week, a small (size 1) natural persistent slab avalanche was observed at treeline on a steep, south-facing road bank. It failed on the sugary, faceted layer 25 cm deep.
We have very few eyes out there. If you do get out please consider reporting in the MIN.
Snowpack Summary
Increasing westerly winds may form fresh winds in the alpine and treeline throughout the day. The upper snowpack has been redistributed by variable winds in the past week. In exposed terrain, slopes may have been scoured back significantly. In sheltered areas, 20-60 cm overlies a generally weak, sugary, facetted lower snowpack. A buried layer of surface hoar sits 25-60 cm deep and remains a layer of concern.
The overall height of snow is highly variable throughout the region with around 40-150 cm in the alpine.
Weather Summary
Sunday night
Increasing cloud cover, trace new snow possible in the early morning. Westerly winds strengthening to 25-40 km/h at ridgetop. Treeline temperatures drop to ~ -20 C.
Monday
A mix of sun and cloud, light snowfall possible with trace accumulation. Northwest winds 10-20 km/h at ridgetop. Treeline temperatures reach a high of -13 C.
TuesdayCloudy with snowfall, up to 5 cm of accumulation expected. Northwest winds 10-40 km/h at ridgetop. Treeline temperatures reach a high of -15 C.
WednesdayA mix of sun and cloud, light snowfall possible with trace accumulation. Westerly winds 5-25 km/h at ridgetop. Treeline temperatures reach a high of -10 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.
Problems
Wind Slabs
Increasing westerly winds may form fresh, reactive wind slabs throughout the day. Be cautious behind ribs and ridges in the alpine and treeline and avoid snow that feels drum like or hollow.
These slabs likely overlay a weak, sugary lower snowpack. If triggered, small avalanches may trigger a bigger avalanche by 'stepping down' to these weak and faceted crystals.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Buried layers of surface hoar and facets have been reactive to human triggering in recent days. The most reactivity has been observed in shaded areas at treeline, where surface hoar may be preserved, and in wind loaded areas at upper elevations, where a cohesive slab has been formed.
Observations on this layer are currently limited. In times of uncertainty such as this, our best defense is to keep terrain choices conservative and reduce your exposure to avalanche terrain where possible.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 5th, 2022 4:00PM
