Avalanche Forecast
Issued: Dec 19th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
CG,
Avalanche Canada
Sniffing out bold lines on untracked slopes with exposure has caught a number of folks by surprise, resulting in several near-misses.
A weak layer primed for human triggering continues to produce isolated large avalanches. The safest way to manage this problem is through conservative terrain use.
Summary
Confidence
Avalanche Summary
Five significant human-triggered avalanches have occurred in the past week, all failing on the Dec 1st surface hoar layer. In the Connaught drainage a size 2.5 was triggered on Balu Peak, on Ursus Minor a skier narrowly avoided being carried over some cliffs, and in the Asulkan valley another avalanche was triggered near the 7 steps. East of the park an experienced group triggered a size 2 avalanche on the same layer with one skier partially buried.
Snowpack Summary
20cm of soft snow overlies variable old surfaces: wind affect; a thin sun crust on steep, solar slopes; or surface hoar in sheltered treeline areas.
The Dec 1 surface hoar, down 50-100cm, continues to produce 'sudden' results in snowpack tests and has been the culprit in several recent human-triggered slides. Below 2100m, a rain crust is buried 40-50cm deep.
In shallow areas the base of the snowpack is faceted and unsupportive.
Weather Summary
No major storms on the horizon, with only minor blips making it to the Selkirks.
Tonight: flurries, 5cm, Alp low -3°C, mod SW winds, 1600m freezing level (fzl)
Wed: Cloudy with flurries, 5cm, Alp high -2°C, mod SW winds, 1600m fzl
Thurs: Cloudy, isolated flurries, Alp high -2°C, light SW winds, 1600m fzl
Fri: Flurries, 5cm, Alp high -3°C, light SW winds, 1400m fzl
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Persistent Slabs
A weak layer of surface hoar down 50-90 cm in the snowpack is at the ideal depth for human triggering and remains reactive. To manage this problem, stick to conservative terrain. Below 2100m this layer may be bridged by a buried rain crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Deeper wind-loaded features in the alpine and at treeline may still hold reactive slabs from the recent snow and warm temps. Allow time for this snow to settle and bond before stepping out into overly committing terrain.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 20th, 2023 4:00PM
