Avalanche forecast

Northwest Inland

Dec 31, 2020 – Jan 1, 2021Avalanche Canada
View on map
Archived · expired 6 years ago

Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map

Highlights

The primary concerns are new wind slabs forming up high and the potential of triggering buried weak layers.

Avalanche problems

  • Wind Slabs

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

    Recent wind from the east is expected to switch to the southwest, meaning new wind slabs may be found on all aspects.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1.5–2.5

    A weak layer may exist around 50 to 100 cm deep, composed of weak and sugary faceted grains above a hard melt-freeze crust. It has been over a week since the last reported avalanche on this layer, but the possibility remains of triggering it where it exists.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2.5–3.5

    The base of the snowpack has been reported as being composed of weak and sugary faceted grains for much of the region. The most likely area to trigger it would be on slopes where the snowpack is thin, such as near rocky outcrops.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

WEDNESDAY NIGHT: Partly cloudy, 10 to 20 km/h west wind, alpine temperature -8 C.

THURSDAY: Cloudy, 20 to 40 km/h southwest wind, alpine temperature -6 C.

FRIDAY: Cloudy with snowfall, accumulation 15 cm, 40 to 60 km/h southwest wind, alpine temperature -7 C.

SATURDAY: Cloudy with snowfall, accumulation 10 cm, 60 km/h southwest wind, alpine temperature -6 C.

Avalanche Summary

The latest reported avalanches were from last weekend, indicating a good amount of wind slab avalanche activity. Looking forward, wind slab activity may continue with elevated winds and some new snow in the forecast. The possibility also remains of triggering deeper weak layers, where they exist.

Snowpack Summary

Up to 5 cm of new snow overlies wind-affected terrain in the alpine and potentially a weak and feathery surface hoar layer, particularly in sheltered treeline terrain. This amount of snow in itself is not sufficient to form destructive avalanches, but thicker wind slabs may be found in exposed terrain features due to recent easterly wind that is forecast to switch to southwesterly.

Around 50 to 100 cm deep, a hard melt-freeze crust from early December may have weak and sugary faceted grains around it. The last reported avalanche activity on this layer was December 17 and 19.

The early-November melt-freeze crust may be found near the base of the snowpack and have weak faceted grains around it. The last reported avalanche activity was near Smithers on December 22. The most likely terrain to trigger it would be in shallow and rocky alpine areas.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Regions covered