Avalanche Forecast
Issued: Dec 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Loose Wet.
swerner,
Avalanche Canada
The snowpack doesn't respond well to rapid change. The impact of the afternoon sun and warm temperatures could bump up the avalanche danger to HIGH. Watch for signs of instability and be conservative with your terrain selection.
Summary
Confidence
Weather Forecast
Wednesday: Sunny with some cloudy periods. Ridgetop winds 15-25/h km fromthe southeast and alpine temperatures + 9 degrees. Freezing levels 3500 m.
Thursday: A mix of sun and cloud. Ridgetop winds 10-20 km/hr from the southeast and alpine temperatures near + 5 degrees. Freezing levels 3000 m.
Friday: A mix of sun and cloud. Ridgetop winds light from the southeast and alpine temperatures + 9 degrees. Freezing levels 3000 m.
Avalanche Summary
Wednesday we may see storm slab avalanches due to rapidly warming temperatures and sun in the afternoon. They may be especially reactive where recent snow sits over a crust. Loose wet avalanches are likely, especially on steep solar aspects at all elevations.
Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything (or don't) while out in the field, please consider sharing via the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!
Snowpack Summary
Last week's snowfall dropped near 30 cm of snow at upper elevations. Strong southwest winds have formed fat pockets of storm slab in lee features above 1400 m.
Forecast sun and rising freezing levels well into the alpine will have the greatest impact on the recent snow promoting slab development. Below 1200 m, most of the recent snow fell as rain on a soggy snowpack. Cooler temperatures overnight may form a thin surface crust on all aspects and elevations.
The snow line currently sits at around 900 m. Snowpack depth rapidly changes with elevation. The snowpack rapidly jumps to around 100 cm deep above 1000 m and between 150 to 200 cm near the mountain tops.
Terrain and Travel
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
- Be cautious of buried obstacles especially below treeline.
Problems
Storm Slabs
A sharp rise in temperature coupled with solar radiation will promote rapid settlement and accelerated slab development in the recent storm snow. Be especially wary of steep south aspects at upper elevations, where recent snow is both receiving direct sun and may be sitting on a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
A rapidly warming snow surface may release loose wet avalanches. Pinwheeling is a good indicator of this type of instability.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 2nd, 2020 4:00PM
