Avalanche forecast

Kootenay Boundary

Jan 6 – 7, 2015Avalanche 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 may be over, but we're not out of the woods yet. Forecasted warming will have a continued destabilizing effect on the snowpack with the potential for very large avalanches. Conservative terrain selection remains critical.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–5
    A problematic layer of weak surface hoar on a hard crust continues to produce avalanches under light loads.  Now down around a meter below the surface, avalanches at this interface are still likely and could be highly destructive.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–4
    Warm temps on Wednesday will likely keep the potent new storm slab touchy.  Ongoing natural avalanches are not out of the question either.

Confidence

Poor - Freezing levels are uncertain

Weather Forecast

Synopsis: Unseasonably mild Pacific air moves into the region in the wake of the exiting storm system. The models are currently showing an Above Freezing air mass between 1200m and 3200m with temps between 0c and +4c on Wednesday and Thursday. Wednesday: Freezing Level: Valley Bottom, Above Freezing Layer 1200 to 3200m; Precipitation: Nil; Wind: Treeline: Light, SW | Ridgetop: Moderate, W.Thursday: Freezing Level: Valley Bottom, Above Freezing Layer 1500 to 3200m; Precipitation: Nil; Wind: Treeline: Light, SW | Ridgetop: Moderate, W.Friday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Moderate, NW.

Avalanche Summary

On Monday storm slabs ran on all aspects/elevations to size 2.5. Many of the reported avalanches started in the storm snow and then stepped down to the mid-December crust/ surface hoar interface.

Snowpack Summary

30 - 60 cm fell across the region over the last 48 hours with moderate southwest winds shifting these accumulations into deeper deposits in lee terrain. Warm temps, with the potential for a little rain will likely keep the storm storm slab sensitive to light triggers. The new snow overlies a variety of old surfaces which include heavily wind-affected surfaces in exposed locations, faceted powder and buried surface hoar in sheltered terrain. Up to 100 cm below the surface, you'll likely find a touchy weak layer of surface hoar sitting on a thick rain crust. This widespread persistent weakness exists at all elevation bands, and continues to be the primary layer of concern for the region. With the recent load of storm snow, I expect this layer to remain active with the potential for large and destructive avalanches. At the base of the snowpack, a crust/facet combo appears to have gone dormant for the time being.

Regions covered