Avalanche forecast

Northwest Inland

Feb 22 – 23, 2013Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–7
    Buried beneath the new snow sits a surface hoar/crust/facet weakness down 40 - 100 cm. This may be sensitive to rider triggering in steeper sheltered terrain or over convex rolls, especially at treeline elevations.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    The new snow may not bond well to the previous snow surface. New wind slabs will likely form on north through east facing terrain near ridge crests.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: There is a brief break between weather systems on Saturday before the next frontal system arrives late Saturday and into Sunday.  Saturday: Cloudy with light snow and possible sunny breaks. The freezing level is around 400 m and winds ease to moderate from the southwest. Sunday: Moderate snowfall – 5-15 cm. The freezing level is around 700 m and winds are moderate to strong from the southwest.Monday: Cloudy but drier. The freezing level remains around 500 m and winds are light from the west.

Avalanche Summary

There are no new reports of avalanches; however, observations have been limited due to poor visibility and weather. I expect natural avalanches in steep lee terrain and the potential for human triggered avalanches.

Snowpack Summary

10-15 cm of new snow has fallen in the past 24 hours. This new snow was accompanied by strong southwest winds forming wind slabs in exposed terrain in lee of ridges, in gullies, and behind terrain features. There are a variety of old interfaces now down 40 - 100cm which include facets, crusts and isolated pockets of surface hoar. There is very limited information about the nature of this interface. I would stress the importance of digging down to find and test weak layers before committing to larger and steeper slopes.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

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