Avalanche forecast

Kootenay Boundary

Feb 18 – 19, 2014Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

The storm and avalanche cycle continue. Time to scale back objectives to low angle conservative terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    Forecast new storm snow may over load the persistent weak layer resulting in very large avalanches. Storm snow avalanches in motion may step down to the buried weak layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–4
    More new snow and wind are forecast overnight. Expect very touchy storm slabs that may step down to the persistent weak layer that is about a metre deep. Natural avalanches and remote triggering are likely.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Wednesday: Expect another fast moving storm bringing 15-20 cm of snow above 1200 metres combined with strong Southwest winds. Precipitation ending by early morning as the winds become moderate Westerly.Thursday: A small pulse of moisture may bring another 3-5 cm to Southern areas of the region. Freezing levels dropping to valley bottoms overnight and rising to about 1000 metres during the day.Friday: Broken skies with some sunny periods and moderate Northwest winds. Freezing level at valley bottoms.

Avalanche Summary

Reports of natural avalanches up to size 3.0, remotely triggered avalanches by skiers or snow machines up to size 2.5, and skier accidentally triggered avalanches up to size 2.0. Just to the North of the region, one avalanche stepped down to the ground and ran full path. Those all happened on Monday, I suspect that there was less natural activity on Tuesday but conditions are primed for human triggering with long propagations. Natural avalanche activity may increase on Wednesday with forecast new snow and wind.

Snowpack Summary

The storm slab is now between 50-100 cm deep. Below the storm snow there is about 20 cm of snow from last week that buried the late January layer of crusts and/or facets and surface hoar. This persistent weak layer from Late January continues to be the sliding layer for natural and human triggered avalanches. The mid snowpack is well settled and strong. The deeply buried weak layers of early season facets and depth hoar have been dormant, but they may become reactive with the right combination of added load and warm temperatures. The forecast new snow and wind are expected to add to the load above the late January weak layer, and may result in avalanches running naturally or increased sensitivity to human triggers at this interface.

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