Avalanche forecast

North Columbia

Dec 26 – 27, 2023Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Weak layers in the mid and lower snowpack have produced large natural and human-triggered avalanches in recent days.

Manage this problem with conservative terrain choices.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Wind slabs have formed on lee features in exposed terrain at treeline and above.

    If triggered, wind slabs have the potential to step down to deeper layers, creating a larger that expected avalanche.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    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

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    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.

Confidence

Moderate

Avalanche Summary

A natural avalanche cycle occurred on Friday night. Several large (size 2 to 3) storm slab, persistent slab, and deep persistent slabs were reported from the alpine and treeline.

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.

Moving forward, natural avalanche activity is expected to taper, but large human-triggered slabs remain possible.

Snowpack Summary

Recent storm snow has been redistributed into wind slab near ridge crests by strong winds. 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

Monday Night

Increasing cloud cover with isolated flurries. Alpine wind southwest 30 to 60 km/h. Treeline temperature -4 °C.

Tuesday

Cloudy with snowfall, up to 5 cm of accumulation. Alpine wind southwest 30 to 60 km/h. Treeline temperature -4 °C. Freezing level rising to 800 m.

Wednesday

A mix of sun and cloud with isolated flurries. Alpine wind southeast 30 to 70 km/h. Treeline temperature -4 °C.

Thursday

Cloudy with snowfall, up to 5 cm of accumulation. Alpine wind south 30 to 60 km/h. Treeline temperature -3 °C. Freezing level rising to 1000 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.
  • 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.

Regions covered