Avalanche Forecast
Issued: Dec 27th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Uncertainty around buried weak layers is best managed with conservative terrain choices.
Avoid steep, convex terrain and rocky areas where triggering is most likely.
Summary
Confidence
Moderate
Avalanche Summary
Over the weekend, many large (size 2 to 3) natural and rider-triggered (some remotely triggered) persistent and deep persistent slabs were reported in the alpine and treeline.
On Tuesday, explosive control in the northern Monashees produced a size 3 deep persistent slab in the alpine and size 2 persistent slab at treeline.
Moving forward, natural avalanche activity has tapered, but large human-triggered slabs remain possible.
Snowpack Summary
Recent strong winds have created heavily wind-affected surfaces in the alpine and treeline. Below treeline a new crust is on or near the surface.
The mid pack contains several layers of note; a layer of surface hoar and a crust down 20 to 40 cm, a significant crust from the early December rain event down around 50 cm and a layer of surface hoar down 50 to 90 cm.
The make up of the lower snowpack is variable throughout the region, in shallower snowpack areas, basal facets exist. This is most concerning in shallow alpine areas.
Weather Summary
Wednesday Night
Mainly cloudy. South alpine wind 15 to 30 km/h. Treeline temperature -4 C.
Thursday
Mainly cloudy with isolated flurries, up to 5 cm accumulation. South alpine wind 15 to 40 km/h. Treeline temperature -4 °C. Freezing level 1400 m.
Friday
A mix of sun and cloud, no new snow. Southeast alpine wind 15 to 30 km/h. Treeline temperature -5 °C.
Saturday
A mix of sun and cloud, no new snow. Southeast alpine wind 10 to 30 km/h. Treeline temperature -2 C, with the potential for an above freezing layer in the alpine.
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.
- Use careful route-finding and stick to moderate slope angles with low consequences.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Use ridges or ribs to avoid areas of wind loaded snow.
Problems
Deep Persistent Slabs
A weak layer of basal facets has produced large natural and human-triggered avalanches in recent days. This problem is most likely to be an issue in shallow snowpack areas in the alpine.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Recent strong southerly winds have formed wind slabs on a variety of aspects in lee features in the alpine and treeline.
If triggered, wind slabs have the potential to step down to deeper layers, creating a larger that expected avalanche.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of surface hoar is down 50 to 90 cm and is still concerning where a significant crust is not found above it.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 28th, 2023 4:00PM
