Avalanche forecast

Kootenay Boundary

Mar 15 – 16, 2013Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate

Highlights

Danger ratings for Saturday are uncertain and will hinge on the amount of refreezing that occurs overnight. If you're traveling on a thickly refrozen snow surface, chances are that avalanche danger's not too bad.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–7
    A weak interface buried in the upper snowpack could still be triggered with a heavy load, like cornice fall, or from a thin-spot trigger point.
  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Recent storm snow may take some time to stabilize, especially if temperatures remain mild.

Avalanche Summary

A widespread avalanche cycle was observed during the storm, which was particularly active as temperatures warmed up. Most avalanches were in the size 1-2 range and failed within, or at the base of, the storm snow. They were observed on all aspects and at most elevations.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Saturday: Light snow, starting late in the day. Moderate to strong W winds. Alpine temperature near -4.Sunday: Light to moderate snow. Moderate to strong NW winds. Alpine temperature near -5.Monday: Light snow. Light SW winds. Alpine temperature near -9.

Snowpack Summary

The recent storm dropped about 15-40 cm snow at upper elevations, while rain soaked the snowpack below about 2000 m. Moist or wet snow at the surface overlies less dense snow, creating “upside-down” storm snow. Strong NW through SW winds may have redistributed snow into wind slabs and created cornices at alpine elevations. Below the storm snow is a layer of buried surface hoar and/or a crust, which increased the reactivity of storm slabs. Deeper in the snowpack, a weak interface buried in mid-February is still on the radar. Although unlikely to be triggered, it remains possible with a very heavy load or from a thin-spot trigger point, particularly at high alpine elevations where the snowpack above this layer is free of supportive crusts.As temperatures cool, wet slab/loose wet avalanche problems should improve, but persistent slab concerns will linger at upper elevations, especially on slopes which didn’t avalanche during the storm.

Regions covered