Avalanche forecast

South Coast Inland

Apr 16 – 17, 2018Avalanche Canada
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Avalanche danger

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

Monday's snowfall accumulation was the highest in the south of the region. Local amounts of around 10 cm are possible on Tuesday. Observe for the bond of the snow with the underlying surface before committing into avalanche terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    Professionals are still travelling cautiously due to a weak layer buried 50 to 100 cm. 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
    Likely
    Size
    1–2.5
    Monday's 10 to 30 cm of snow may not bond well to varying snow surfaces. Older slabs from the weekend have been most reactive adjacent to ridges in wind-loaded terrain. Watch your overhead exposure, as cornices could trigger slabs on slopes below.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

TUESDAY: Cloudy with light snowfall, accumulation 2 to 5 cm with possible higher amounts in localized areas, moderate to strong west winds, alpine temperature -6 C, freezing level 1400 m.WEDNESDAY: A mix of sun and clouds, light south winds, alpine temperature -5 C, freezing level 1500 m.THURSDAY: Morning sun and afternoon clouds, light southwest winds, alpine temperature -4 C, freezing level 1600 m.

Avalanche Summary

Large (size 3) persistent slab avalanches were observed in the far north of the region over the weekend. They were about 60 to 80 cm deep, on northwest to east aspects, between 1800 and 2200 m, and failed naturally on the weak surface hoar layer described in the Snowpack Summary section. They propagated widely across the slopes. Otherwise, many slides in the recent storm snow were observed, often triggered by cornice failures.

Snowpack Summary

10 to 30 cm of new snow, with the most in the south of the region, has been redistributed into lee terrain features from northeast winds. This overlies variable surfaces, including wind slabs at high elevations, a sun crust on south aspects, and a temperature crust on all aspects up to 1900 m. Previous wind slabs are up to 1 m deep from strong south winds. On ridges, cornices are reported to be large and fragile.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 50 to 100 cm. This layer is spotty in its distribution and has recently produced large and destructive 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.The mid and lower snowpack are well-settled and strong.

Regions covered