Avalanche forecast

Northwest Coastal

Apr 5 – 6, 2017Avalanche Canada
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Avalanche danger

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

Wind slabs and cornices are a serious concern at higher elevations. Be cautious as you climb and continually reassess conditions.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Very strong winds on Tuesday night and Wednesday likely formed reactive wind slabs in the lee of exposed terrain.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    Large cornices may become weak with daytime warming or during periods of stormy weather.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3
    A weak layer from February produced several large human triggered avalanches at the end of March, and may still react in shallow areas. Heavy loads such as a small avalanche or a cornice fall are also possible triggers.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

THURSDAY: Linger flurries with another 5-10 cm easing off through the day, southeast wind dropping to 25 km/h, freezing level up to 1200 m after an overnight freeze.FRIDAY: Mostly cloudy with isolated flurries, moderate southeast wind, freezing level up to 1400 m after an overnight freeze.SATURDAY: 5-10 cm of new snow, light southeast wind, freezing level around 1200 m.

Avalanche Summary

Preliminary observations from Wednesday report several natural wind slabs in steep alpine features around Bear Pass (up to size 2.5). Several avalanches were triggered by cornice falls earlier in the week, including one size 2.5 persistent slab avalanche on the February weak layer. A snowmobiler had a close call with a cornice fall on the weekend at South Douglas (click here for MIN report).

Snowpack Summary

Touchy wind slabs exist as higher elevations, as Tuesday night's storm delivered 15-20 cm of snow above 1000 m with strong to extreme winds. Extensive wind affect is expected in exposed terrain. An overnight freeze will likely form a crust at lower elevations that will deteriorate with the heat of the day. It may still be possible to trigger a large avalanche on the late February persistent weak layer. This combination of weak facets and crusts is buried 100-150 cm deep. Recent snowpack tests found moderate sudden results on the layer in the May Creek area on an east aspect around 1200 m.

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