Avalanche forecast

South Coast Inland

Apr 7 – 8, 2018Avalanche Canada
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Avalanche danger

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

Recent snowfall with strong winds has produced new slabs at higher elevations. Expect avalanche activity to increase on southerly aspects if the sun comes out.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    Cornices are very large and fragile. Give them a large berth when on ridges and avoid travelling underneath them, as they can trigger large avalanches on slopes below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A weak layer buried 40 to 70 cm is still surprising people and producing large and destructive avalanches. Be particularly cautious around upper treeline and alpine terrain on shady aspects, where this layer is most likely to be a problem.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Recent snowfall has formed new slabs. Expect thicker slabs in lee features due to strong southerly winds. Slab or loose wet avalanches could release naturally when the sun is out or the air temperature warms.

Confidence

Moderate -

Weather Forecast

SUNDAY: A mix of sun and cloud, light westerly winds, alpine temperature -3 C, freezing level 1500 m.MONDAY: A mix of sun and cloud, light southwesterly winds, alpine temperature -3 C, freezing level 1600 m rising to 2000 m by late afternoon.TUESDAY: Mostly cloudy with afternoon precipitation, accumulation 5 mm, alpine temperature 0 C, freezing level 2600 m dropping to 2000 m.

Avalanche Summary

On Friday, a large (size 2.5) persistent slab avalanche was triggered by a cornice on a northeast aspect around 1900 to 2200 m.  The slab likely released on the weak layer described in the Snowpack Summary.  Other similar large avalanches were observed, as described in this MIN post.Small to large (size 1 to 2) wind slabs were also reactive to skiers and large loads, generally failing in alpine terrain in immediate lee terrain features.  Loose wet avalanches were observed across the region on all aspects to size 1.5.

Snowpack Summary

Around 20 cm of snow and strong southwesterly winds created new slabs at higher elevations.  This snow overlies various old surfaces including previous storm snow, melt freeze crusts on sunny aspects, and old wind slabs.  On ridges, cornices are reported to be large and fragile. At lower elevations, precipitation fell as rain and created wet snow conditions.A weak layer consisting of surface hoar, facets, or a sun crust from late March is now buried about 40 to 70 cm. This layer is spotty in its distribution. It is mostly likely to be problematic on shady aspects between 1900 m and 2250 m.The mid and lower snowpack are strong and well-settled.

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