Avalanche forecast

Northwest Coastal

Jan 22 – 23, 2022Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Watch for changing conditions as a rise in temperature tests the upper snowpack. The presence of buried surface hoar below the storm snow means that reactivity could persist into today.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5

    Earlier in the week, 30 to 50 cm of new snow formed a storm slab problem in sheltered areas. In wind-exposed areas, strong southwest winds have built deep deposits of wind slab in lee terrain features. In the past few days, these slabs have been quite touchy with wide propagation observed where they overlie a weak layer of surface hoar which sits on a hard melt-freeze crust below 1300m. The presence of this weak layer means that reactivity may persist today, particularly with a rise in temperatures promoting rapid settlement in the upper snowpack. 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    If the sun comes out today, solar radiation compounded by warm temperatures may have a destabilizing effect on the upper snowpack. Wet loose avalanches have the potential to step down to buried weak layers and entrain large amounts of mass.

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Stormy weather continues up north, while the south of the region sees a temperature inversion ushering in warm temperatures at higher elevations. 

Friday Overnight: Cloudy, with up to 5 cm of new snow in the north of the region. Strong to extreme southwest winds. Freezing level around 1000m.

Saturday: In the south of the region, partially cloudy skies with the potential for a temperature inversion with above 0 C temperatures in the alpine. In the north, mainly cloudy, up to 10 cm of new snow, accompanied by moderate to strong southwest winds. 

Sunday: Cloudy, up to 5 cm of new snow accumulation. Moderate to strong westerly winds. Freezing level around 1000m.

Monday: Partially cloudy, light northwest winds. Freezing level rising to 2500m.

Avalanche Summary

On Thursday, numerous natural, human-triggered, and remote-triggered storm slab avalanches up to size 2.5 were observed throughout the region. A buried layer of surface hoar, and below 1300m a thick melt-freeze crust likely contributed to the reactivity and wide propagation of these storm slabs.

Snowpack Summary

On Thursday, 30 to 50 cm of snow fell, with snow switching to rain up to around 1000 m around the Terrace area. Storm slabs rapidly built during the storm along with wind slabs in terrain exposed to the wind from strong southwest wind. In some areas, these slabs overlie a weak layer of buried surface hoar and a hard melt-freeze crust below 1300 m. The presence of these weak layers means reactivity might persist.

A layer of sugary facetted grains may be found about 80 to 130 cm deep, which formed during the cold spell in late December to early January. To date, this layer has only been problematic in the northern half of the region.

The remainder of the snowpack is strong in the south of the region. In the north of the region, the base of the snowpack consists of faceted grains around a melt-freeze crust, which is currently dormant.

Terrain and Travel

  • Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.

Regions covered