Bulletin d’avalanche

North Columbia

Dec 29 – 30, 2023Avalanche Canada
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Archivé · expiré 3 years ago

Danger d’avalanche

Sun
Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

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.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1.5–3

    A layer of surface hoar is down 50 to 90 cm and is still concerning where a significant crust is not found above it.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3.5

    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.

Confidence

Moderate

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.

Régions couvertes