Avalanche Forecast
Issued: Dec 20th, 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.
JH,
Avalanche Canada
A persistent weak layer of surface hoar mid-snowpack, is primed for human triggering. The safest way to manage this problem is through conservative terrain use.
Pushing into bold terrain in search of untracked lines, has resulted in several near-misses recently.
Summary
Confidence
Avalanche Summary
On Wednesday, there were a few size 1-2 windslab avalanches from the steep terrain above the Eastern portion of the highway corridor.
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.
Snowpack Summary
Up to 25cm 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 close calls from human-triggered avalanches. Below 2100m, a rain crust is buried 40-50cm deep.
In shallow areas the base of the snowpack is faceted and unsupportive.
Weather Summary
A relatively benign weather pattern is in place over our area until the end of the day Friday.
Tonight: Isolated flurries, Alpine low -4°C, 1500m freezing level (fzl), Light SW ridgetop winds.
Thurs: Scattered flurries (5cm), High -2°C, 1700m fzl, Light SW wind.
Fri: Flurries (15cm), Low -8°C, High -3°C, 1400m fzl, Moderate SW wind.
Sat: Mixed sun/cloud, Low -13°C, High -9°C, Light W wind.
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.
- 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
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 21st, 2023 4:00PM
