Avalanche forecast

North Columbia

Jan 29, 2018Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Warm storm coming! Avoid all avalanche terrain during periods of heavy snowfall, including exposure to overhead hazard.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–4
    Several weak layers are buried in the snowpack, creating very large avalanches when triggered.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Heavy snowfall and warming temperatures are a recipe for widespread avalanches. A storm slab could step down to a deeper weak layer, creating a surprisingly large avalanche.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Monday: 15 cm snow Sunday overnight into Monday. 15-25 cm additional snow during the day. Moderate to strong south-westerly winds. Alpine temperature warming in the afternoon to near -2. Freezing level rising to 1200m in the afternoon. Tuesday: 5-15 cm snow. Moderate south-easterly winds. Alpine temperature near -5. Wednesday: Isolated flurries (up to 5cm possible). Moderate southerly winds. Alpine temperature near -5.More information can be found in the Mountain Weather Forecast.

Avalanche Summary

On Saturday a human-triggered Size 2.5 avalanche was reported near 2300m on a south west aspect in Glacier National Park. See the MIN report for incident details. Locally heavy snowfall in the Monashees on Saturday produced a widespread natural avalanche cycle in the afternoon. A widespread natural avalanche cycle is expected with Monday's storm, with the potential for some surprisingly large avalanches given how many persistent weak layers exist in the snowpack.

Snowpack Summary

The current snowpack is complex, with three active weak layers that we are monitoring. The recent storm snow fell with strong south winds, producing wind slabs in lee features at treeline and alpine elevations and in open areas below treeline.1) 60-90 cm of storm snow sits on a crust and/or surface hoar layer from mid-January. The crust is reportedly widespread, with the possible exception of high elevation north aspects. The mid-January surface hoar is 5 to 20 mm in size and was reported at treeline elevations and possibly higher. 2) Deeper in the snowpack, the early-January persistent weak layer is 90 to 120 cm below the surface. It is composed of surface hoar on sheltered slopes as well as sun crust on steep solar aspects and is found at all elevation bands. Snowpack tests show sudden fracture characters and signs of instability such as whumpfs, cracking and avalanches. 3) Another weak layer buried mid-December consisting of a facet/surface hoar/crust combination is buried 100 to 150 cm deep. It is most problematic at and below tree line.

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