Avalanche forecast

Sea To Sky

Feb 7 – 8, 2016Avalanche Canada
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Avalanche danger

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

Warming and solar radiation will drive the Avalanche Danger over the next few days. Use extra caution if solar radiation is strong on Monday.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Cornices are huge and will become weakened by forecast warming and solar radiation. They can be destructive by themselves, and may also become the trigger for a large slab avalanche on the slope below. Use extra caution around ridge crests.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Although recently formed storm slabs have gained significant strength, they may remain sensitive to rider triggering in high elevation lee terrain.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–4
    Rising freezing levels and solar radiation on Monday and Tuesday will spark a round of loose wet avalanche activity on sun-exposed slopes. Loose wet avalanches may also step down to deeper, more destructive layers.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Monday

Weather Forecast

On Monday expect overcast skies in the morning with gradual clearing in the afternoon. Tuesday should be mainly clear with increased cloud forecast for Wednesday.. Ridgetop winds should remain mainly light from the southwest. Freezing levels will climb to about 3500m for Monday and Tuesday, and then drop to about 2200m by Wednesday.

Avalanche Summary

In the wake of Friday's storm, natural storm slab activity was noted throughout the region to size 3. Storm slabs have become much more difficult to trigger, but may still be sensitive to light inputs in high elevation lee terrain. Looking further ahead, rising freezing levels and solar radiation on Monday should spark a round of loose wet avalanche activity on sun-exposed slopes. Warming will also increase the likelihood of triggering cornice falls, wet slabs and deep and destructive persistent slabs.

Snowpack Summary

On Friday between 60 and 100cm of new snow fell. Strong to extreme southwest winds shifted these accumulations into deep and dense storm slabs. Cornices were already large before the storm, and new growth is expected to be fragile. About 70-100cm below the surface, you likely find a rain crust which formed on January 28th. This crust is widespread and exists up to about 2050m. Where it still exists, the mid-January surface hoar layer may be found between 130 and 200 cm below the surface. The combination of ongoing heavy storm loading and warm temperatures has flushed out this weak layer in most areas. That said, warming and solar radiation forecast for the next few days may be what it takes to wake up this deep and destructive persistent weak layer.

Regions covered