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.
jleblanc,
Avalanche Canada
Use extra caution at higher elevations with shallow snowpack, especially where the buried crust is breakable. A tricky layer of surface hoar is continuing to produce large avalanches.
Summary
Confidence
Avalanche Summary
On Tuesday, a skier remotely triggered a large size 2.5 avalanche in the Esplanade Range. This persistent slab occurred on a southeast alpine slope and ran on the concerned surface hoar layer 40-60 cm deep. Small loose dry avalanches and skier-triggered wind slabs were also reported on isolated alpine features.
If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).
Snowpack Summary
The region received up to 10 new snow recently, bringing the total of fresh snow to 20-30 cm. Moderate to strong westerly winds have redistributed 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 40 to 60 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
Wednesday Night
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 30 to 40 km/h, treeline temperature -3 °C, freezing level at 1500 m.
Thursday
Cloudy with isolated flurries, trace accumulation, alpine wind southwest 30 to 40 km/h, treeline temperature -3 °C, freezing level at 1700 m.
Friday
Cloudy, light snow up to 5 cm, alpine wind southwest 40 to 50 km/h, treeline temperature -3 °C, freezing level at 1700 m.
Saturday
Mix of sun and clouds, no precipitation, alpine wind northwest 30 to 40 km/h, treeline temperature -6° C, freezing level at 800 m.
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.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Persistent Slabs
Choose terrain assuming the weak layers capable of producing large avalanches. The layers of concern are a surface hoar layer buried 40 to 60 cm deep and weak facets at the base of the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Human-triggering wind slab avalanches remain 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 21st, 2023 4:00PM
