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.
jleblanc,
Avalanche Canada
A buried surface hoar layer remains the primary concern. As you gain elevation, assess continually the conditions. Read our Forecasters' Blog for details of the persistent slab problem.
Summary
Confidence
Avalanche Summary
On Monday, a large size 2.5 natural avalanche was observed at 2400 m, in the Esplanade Range. The persistent slab triggered a sympathetic avalanche on a slope nearby.
On Sunday, groups triggered persistent slab avalanches (size 2 and size 2.5) on Balu Peak, Glacier National Park. They occurred above 2200 m and are suspected to have failed on a buried surface hoar layer. Although they occurred in neighboring region, this weak layer remains a concern throughout both regions.
Snowpack Summary
10 to 25 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
Tuesday Night
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 30 to 40 km/h, treeline temperature -4 °C, freezing level at1500 m.
Wednesday
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 40 to 50 km/h, treeline temperature -3 °C, freezing level at 1800 m.
Thursday
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 40 to 50 km/h, treeline temperature -3 °C, freezing level at 1700 m.
Friday
Cloudy, light snow 5 cm, alpine wind southwest 40 to 50 km/h, treeline temperature -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Keep in mind that human triggering potential persists as natural avalanching tapers off.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Persistent Slabs
30 to 60 cm deep, a surface hoar layer is likely to be triggerable in areas without a rain crust, and weak facets at the base of the snowpack. Choose terrain assuming the buried weak layers capable of producing large avalanches.
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. Be especially cautious as you transition into wind affected terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 20th, 2023 4:00PM
