Avalanche Forecast
Issued: Dec 22nd, 2024 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Parks Canada,
Avalanche Canada
The recent snow has helped the ski quality, but strong alpine winds have created new wind slabs in lee alpine areas. While the wind slabs may seem manageable, the primary concern is the threat of superficial slabs stepping down to the deep persistent weakness resulting in full-depth avalanches.
Summary
Confidence
Moderate
Avalanche Summary
The ski hills continued to trigger deep persistent slabs with explosives on Saturday and Sunday, up to size 2.5, failing on the basal facets/crust.
On flights and field trips we have observed failures at both the new wind slab interface and the deep persistent problem since the latest storm on Dec 18, but natural avalanche activity has slowed down in the past couple days.
Snowpack Summary
4-8 cm of snow on Sunday over ~20 cm of storm snow from last week. This snow, combined with strong W/SW winds, created wind slabs in alpine lee areas and down into treeline.
The mid and lower snowpack is faceted and weak, with facet/crust interfaces near the ground. This is more pronounced east of the divide, while western regions display a deeper snowpack with fewer facets.
Snowpack depths at tree-line are about 60 cm in eastern areas and closer to 100 cm west of the divide.
Weather Summary
Becoming cloudy overnight on Sunday with moderate to strong SW winds at ridgetops that continue into Monday. A mix of sun and cloud on Monday with more cloud to the west, and treeline temperatures steady around -6°C.
Terrain and Travel Advice
- Avoid freshly wind-loaded features, especially near ridge crests, rollovers, and in steep terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
Problems
Wind Slabs
Moderate to strong south through west winds continue to build slabs in lee features in the alpine and down into treeline. The new snow with continued winds on Monday will promote further slab development. This is a particular concern where wind slab failures could step down to deeper facet layers.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak facets and depth hoar associated with crusts near the base of the snowpack continue to produce slab avalanches 60-100 cm deep. Any area with a stiffer slab over the mid-pack and deep facets has the potential to generate an avalanche that steps down to the deep layers and end up being quite large.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 23rd, 2024 4:00PM
