Avalanche Forecast
Issued: Dec 11th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
bchristie,
Avalanche Canada
Start with small slopes, and watch for signs of instability like shooting cracks or whumpfs.
Investigate for crusts and buried weak layers that are good sliding surfaces for avalanches.
Summary
Confidence
Avalanche Summary
On Saturday, some small (size 1) human triggered storm slab and loose dry avalanches were reported in the recent storm snow.
We're uncertain on whether avalanches could still release on the surface hoar layer described in the Snowpack Summary, so travel cautiously until there is evidence it is bonding or has been destroyed.
Snowpack Summary
30-55 cm of snow sits on a 5-15 cm melt-freeze crust. Below this crust you may find moist snow to ground, or dry, possibly refrozen snow and a layer of somewhat preserved surface hoar, ~60 cm deep.
Triggering this layer is most likely in areas where the overlying crust is thinner and less supportive, and where it didn't already fail in last weeks snow storm. We recommend treating this layer as suspect while we await more observations.
Snow depth is generally 70-110 cm at treeline, tapering quickly below. The mid and lower snowpack may contain a weak facet layer in shallower areas.
Weather Summary
Monday Night
Mostly clear. No new snow expected. Light north ridgetop wind. Treeline temperature around -5°C.
Tuesday
Sunny. No new snow expected. Light to moderate southwest ridgetop wind. Treeline temperature around -4°C.
Wednesday
Mostly sunny, increasing cloud in the afternoon. No new snow expected. Moderate to strong south ridgetop wind. Treeline temperature around -4°C, with possible temperature inversion in the alpine.
Thursday
Cloudy. 5-10 cm of snow expected. Moderate west ridgetop wind. Treeline temperature around -6°C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Uncertainty is best managed through conservative terrain choices at this time.
- 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
Storm Slabs
Storm slabs may be triggerable by riders, especially where wind has moved snow into leeward terrain features on north and east aspects. The underlying crust could also be a sliding layer, but the recent storm snow seems to be bonding so far.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
This surface hoar layer was seen after the rain storm in some areas, 4-20mm big. As the moisture in the snowpack migrates and freezes, the weak layer may melt or bond, and crusts above it may become more robust, making it harder to trigger.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 12th, 2023 4:00PM
