Avalanche forecast

Sea To Sky

Apr 11 – 12, 2018Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The calm before the storm. Storm slabs are reactive to human triggers in the alpine, especially on northerly (leeward) aspects where deeper slabs exist due to wind loading.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3.5
    A weak layer buried 60 to 90 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
    1–2.5
    Storm slabs are building at upper elevations. Slabs will be thicker in lee features, as the snow will fall with strong southwest winds. If the sun comes out the new snow will likely become unstable and reactive.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Thursday: Cloudy with some sunny periods. New snow up to 5 cm and strong southwest wind at ridgetop. Freezing level 1300m.Friday: Stormy. New snow 15-25 cm through the day. Ridgetop winds strong from the South. Saturday: The storm continues bringing another 15-20 cm. Ridgetop winds strong from the southwest. Freezing levels 1400 m.

Avalanche Summary

On Tuesday, limited alpine observations existed due to weather. Above 1900 m skier triggered isolated slabs up to size 1 were easily triggered. At lower elevations small loose wet natural avalanche activity occurred. Avalanche activity will be on the rise with the incoming storm. Its still winter out there!

Snowpack Summary

Warm temperatures and rain have moistened the snow surface on all aspects and at all elevations with new snow accumulations in the alpine up to 15 cm. Reactive storm slabs and wind slabs are building with continued snow and strong southwest winds. Ridgelines are heavily corniced and if they fail they would act as a trigger on the slope below. A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 60 to 120 cm down. This layer is spotty in its distribution but has recently produced large avalanches. It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.Below this, the snowpack is well-settled and strong.

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