Avalanche forecast

South Coast Inland

Feb 18, 2018Avalanche Canada
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Archived · expired 9 years ago

Avalanche danger

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

Highlights

Fresh storm slabs will be reactive to human-triggers, especially in wind-affected terrain.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1.5–3.5
    Large, looming cornices have formed along ridgelines. They need to be given an extra wide berth from above and below. A large cornice collapse in the north of the region may have the ability to trigger a deeply buried weak layer.
  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5
    30-50 cm of fresh snow from Saturday's storm has formed reactive storm slabs, especially in wind-affected terrain at higher elevations.

Confidence

Moderate -

Weather Forecast

SUNDAY: Gradual clearing and cooling as Arctic air pushes into the region, moderate to strong northeast wind, alpine high temperatures around -18 C in the north and -12 in the south.MONDAY: Sunny, moderate northeast wind, alpine high temperatures around -15 C.TUESDAY: Mostly sunny, light wind, alpine high temperatures around -12 C.

Avalanche Summary

Preliminary reports from Saturday include small dry loose avalanches in steep terrain in the Duffey area. No reports have come in from the south of the region, but natural slab activity was likely given the intense snowfall. Wind slabs activity has been reported in northern parts of the region over the past week, including a size 2 skier-triggered avalanche in a cross-loaded gulley feature at treeline on Friday.

Snowpack Summary

Saturday's storm delivered ample snow to the region, with the Duffey area receiving at least 30 cm and Coquihalla receiving 40-50 cm. To the north, the storm snow is primarily low density with the exception of exposed terrain where wind has formed slabs. To the south, the snow is likely denser and formed a more widespread slab.A few interfaces buried last week could potentially support wide propagations in the storm slabs. These include scoured crusty surfaces on south-facing alpine slopes, a melt-freeze crust up to 1700-1900 m, and hard wind damaged snow in exposed terrain.The mid-January crust is now buried beneath 80-150 cm of settled snow and may remain sensitive to large triggers - especially in thinner snowpack areas in the north part of the region. Large, looming cornices exist, they are fragile, and they demand respect. Cornice falls are very effective triggers for avalanches on the slopes below them.

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