Avalanche forecast

Sea To Sky

Apr 21 – 22, 2018Avalanche Canada
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Avalanche danger

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

Warming and solar radiation will drive the avalanche danger in the coming days. Watch for conditions that change throughout the day, and be cautious of overhead hazards.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    New snow and strong winds from Friday night have formed new wind slabs in upper elevation lee terrain. Although they're likely to gain strength quickly, I'd remain cautious around ridge crests and in gullies.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5
    Professionals are traveling cautiously in shaded upper treeline and alpine terrain due to a weak layer buried 60 to 140 cm below the surface. Forecast warming and cornice failures will likely re-activate this destructive interface in isolated terrain

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2.5
    Warming and solar radiation are expected to trigger loose wet avalanches, especially in steep, sun-exposed terrain. Loose wet avalanches can be pushy and entrain mass quickly. Warming may also trigger destructive cornice failures.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure will develop for the forecast period bringing clear skies and light ridgetop winds. The freezing level will hover around 1800m on Sunday and then rise to about 2600m for Monday and Tuesday.

Avalanche Summary

No new avalanches were reported at the time of publishing this bulletin, although I'm sure there was a round of wind slab activity on Saturday in response to new snow and strong overnight winds. Loose wet avalanches and cornice falls are expected to become problematic with warming and solar radiation forecast for Sunday and Monday. Warming also has the potential to wake-up the late March crust interface with the possibility of surprisingly large and destructive avalanches.

Snowpack Summary

New snow and wind on Saturday formed fresh wind slabs in upper elevation lee terrain. The new snow overlies settled storm snow on shaded aspects above 2000m and a melt-freeze crust in most other areas.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 60 to 140 cm below the surface. This layer is spotty in its distribution and has recently produced large and destructive avalanches. It is most likely to be problematic on west, north, and east aspects between 1900 m and 2250 m. Professionals are treating this layer very cautiously and avoiding steep, unsupported terrain. Read Conditions report here.The mid and lower snowpack are well-settled and strong.

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