Avalanche Forecast
Issued: Dec 18th, 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.
lbaker,
Avalanche Canada
Buried weak layers remain the primary concern. Use good travel habits to avoid getting caught off guard.
Read our Forecasters' Blog for details on the persistent slab problem.
Summary
Confidence
Moderate
Avalanche Summary
On Sunday, explosives control triggered a size 1.5, persistent slab avalanche on a north aspect at 2450 m.
In Glacier National Park, a group triggered a size 2.5 and a size 2, persistent slab avalanche on Balu Peak. These avalanches all occurred above 2200 m and are suspected to have failed on the buried surface hoar layer. Though these avalanches occurred in a neighboring region this weak layer remains a concern throughout both regions.
Snowpack Summary
5 to 20 cm of recent snow has been redistributed by strong westerly winds into deep pockets in lees. This overlies a variety of surfaces including a surface hoar layer, sun crust, and wind-affected snow.
A prominent rain crust is found 30 to 50 cm deep and has been reported to extend as high as 2300 m around Invermere and 2000 m around Golden. A layer of surface hoar is also found at this depth and is a particular concern in areas without a thick crust.
The lower snowpack contains large weak snow grains and in some places a hard crust near the ground. Typical snowpack depths at treeline are 60 to 110 cm, and taper rapidly below treeline.
Weather Summary
Monday Night
Mainly cloudy, alpine wind southwest 25 km/h, treeline temperature -4 °C.
Tuesday
Cloudy with isolated flurries, 1 to 4 cm accumulation, alpine wind southwest 30 to 40 km/h, treeline temperature -4 °C.
Wednesday
Mainly cloudy with isolated flurries, trace accumulation, alpine wind west 40 to 50 km/h, treeline temperature -3 °C.
Thursday
Mix of sun and cloud with isolated flurries, trace accumulation, alpine wind west 40 to 50 km/h, treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be especially cautious as you transition into wind affected terrain.
- Keep in mind that human triggering potential persists as natural avalanching tapers off.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Persistent Slabs
Choose terrain assuming there are buried weak layers capable of producing large avalanches. A 30 to 60 cm deep surface hoar layer is triggerable in areas without a rain crust, and weak facets sit at the base of the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Human-triggering wind slab avalanches remains possible on leeward terrain features such as ridge crests and roll-overs in the alpine.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 19th, 2023 4:00PM
