Avalanche forecast

Kootenay Boundary

Mar 16 – 17, 2014Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Fresh storm accumulations may be particularly touchy in higher, wind-exposed terrain and in areas where they overlie buried surface hoar. Solar radiation on Monday may also increase reactivity within the storm snow.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Rain-soaked snow may continue to react as a loose wet avalanche in steep lower elevation terrain. If the sun comes out on Monday, loose wet avalanches may be possible at all elevations.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Deep persistent weaknesses buried over a month ago continue to show reactivity in snowpack tests. Avalanches on persistent weakness are possible at all elevation bands and would be highly destructive in nature.

Confidence

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

Weather Forecast

Overview: A generally dry ridge of high pressure will develop on Monday and Tuesday with the passing of Sunday's frontal system. Another pulse will bring moisture to the region on Wednesday.Overnight Sunday: Up to 10cm of snow / Moderate to strong westerly winds / Freezing level at about 1500mMonday: Light flurries in the morning with a mix of sun and clouds / Light to moderate westerly winds with strong gusts / Freezing level at 1500mTuesday: Mix of sun and cloud / Light northwesterly winds with strong gusts / Freezing level at 1500mWednesday: Moderate snowfall / Moderate westerly winds / Freezing level at 1500m

Avalanche Summary

Reports from recent days include a remotely triggered deep persistent slab avalanche with a heavy trigger in a low angle meadow. The slab released on the facet/crust weakness down 80-100 cm on a NW aspect at 2100 m. At the time of publishing on Sunday, we had very few reports from the field. That said, I'm sure there was a decent round of loose wet avalanche activity at lower elevations where rain fell. Storm/wind slab activity is likely to have occurred at higher elevations. Forecast solar radiation on Monday and Tuesday may trigger ongoing avalanche activity.

Snowpack Summary

Up to 35cm of accumulated storm snow was blown by strong winds into much deeper deposits in lee terrain. The recent snow overlies a fairly widespread melt-freeze crust which seems to exist on all aspects up to about 2000m. The bond between the new snow and the crust may be weak, especially where surface hoar crystals (up to 8mm) sit above the crust. With forecast solar radiation I would expect the new storm slab to increase in reactivity.The deeper facet/crust persistent weakness buried at the beginning of February, now down 100-150 cm, is still the primary concern among most professional operators. The interface continues to show "sudden" shears in snowpack tests and has the potential to produce very large and destructive avalanches.I would suspect cornices are now large and potentially unstable.

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