Avalanche Forecast
Issued: Dec 28th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent Slabs.
dnylen,
Avalanche Canada
Uncertainty around persistent weak layers is best managed with conservative terrain choices and minding overhead hazard.
Steep and convex rocky areas are where triggering is most likely.
Summary
Confidence
Avalanche Summary
On Wednesday, a few large (size 2 to 3) natural and explosive triggered persistent and deep persistent slabs were reported in the alpine. A few smaller (size 1.5) natural windslab and storm slabs have also been seen.
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
Wind affected snow is present on the surface 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
Thursday night
Mainly cloudy with isolated flurries, 1 to 3 cm accumulation. Southwest alpine wind 20 to 40 km/h. Treeline temperature -8 °C.
Friday
A mix of sun and cloud, no new snow. Southeast alpine wind 10 to 30 km/h. Treeline temperature -4 °C.
Saturday
A mix of sun and cloud, no new snow. Southeast alpine wind 10 to 40 km/h. Treeline temperature -2 C, with the potential for an above freezing layer in the alpine up to 2500 m.
Sunday
Mainly cloudy with isolated flurries, 1 to 3 cm accumulation. Southwest alpine wind 10 to 30 km/h. Treeline temperature -2 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.
- 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.
- Overhead hazard may not be obvious, evaluate prior to commiting to terrain.
Problems
Deep Persistent Slabs
A weak layer of basal facets means shallow snowpack areas are most likely trigger points. The possibility for large natural avalanches means that overhead hazard should be given due caution.
Aspects: All aspects.
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 29th, 2023 4:00PM
