Avalanche forecast

South Coast

Feb 22 – 23, 2014Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Conditions are primed for triggering avalanches. Conservative decision making is essential. Check out the latest forecaster blog for more discussion on the current conditions.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–5
    Strong winds have formed fresh wind slabs in lee and cross-loaded terrain. A thin wind slab could  potentially trigger the deeper persistent weakness and result in a very large avalanche.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–7
    A persistent weakness, now down 60-80 cm in the northern part of the region and 100-150 cm in the south, is primed for rider triggering. This tricky problem has the potential for wide propagation and very large avalanches.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Synopsis: One more warm front should pass across the South Coast late Sunday spreading light to moderate snowfall through Monday morning. A ridge of high pressure builds in on Monday kicking off a drying trend. Sunday: Flurries or light snow – 5-10 cm. The snow line is near sea level. Ridge winds are moderate from the W-NW. Monday: Flurries ending early, followed by a mix of sun and cloud. The freezing level is around 500 m. Winds are moderate from the north, easing to light. Tuesday: A mix of sun and cloud. The freezing level is around 1000 m. Winds are light.

Avalanche Summary

A number of very large (size 3-4) natural and explosive triggered slab avalanches occurred near the Coquihalla Pass on Friday. These events were in response to rapid loading from new snowfall and strong winds and showed impressive propagation. In other areas natural activity was limited to relatively small moist loose snow avalanche from solar aspects. Whumpfing and cracking continue to be reported and the potential for triggering the mid-February persistent weakness remains high.

Snowpack Summary

In the last week, the northern part of the region received over 1 m of new snowfall, while southern areas saw almost 2.5 m (and counting). Strong winds have created dense wind slabs on exposed lee slopes and in cross-loaded terrain features. In the southern portion of the region the new snow sits on a crust/facet combination along with old wind slabs on lee slopes. In the northern part of the region one can add surface hoar to the crust/facet/slab combination. Recent snowpack tests generally give moderate sudden "pops or drops" shears on this weakness and show potential for wide propagation. The mid and lower snowpack are generally strong and well-settled. Although basal facets and depth hoar are likely to exist in the north of the region, giving us a low probability, but high consequence of a large destructive avalanche.

Regions covered