Avalanche forecast

South Columbia

Feb 19 – 20, 2013Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–5
    Recently formed wind slabs are hidden under a dusting of low-density snow. Watch for triggering in the lee of ridge crests and in gullies.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–6
    There are older layers of buried surface hoar and crusts that are unlikely to be triggered by the weight of a skier or sledder, but may be triggered by large additional loads like cornice fall or a slab avalanche in motion.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    This storm slab is expected to continue to be reactive where it overlies a weak layer of surface hoar and sun crusts. Reactivity is likely to increase with exposure to solar radiation.

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Wednesday: Mix of sun and cloud / Light north winds / Freezing level at 800mThursday: Light snowfall intensifying in the evening / Moderate south winds / Freezing level at 900mFriday: Heavy snowfall / Moderate to strong south winds / Freezing level at 1100m

Avalanche Summary

Explosives control produced a couple of size 2 avalanches in the region. I have limited info regarding these events. No other new avalanches were reported.

Snowpack Summary

Variable amounts of low density snow add to the recent storm slab that is between 20-50 cms across the region. These light accumulations may overlie wind slabs which formed a few days ago in the alpine and at treeline. The recent storm slab is expected to remain reactive where it is sitting on the weak surface hoar layer that was buried on February 12th. The recent storm slab has also been reactive on Southerly aspects where a sun crust formed during the period from February 8th-11th. Warming from solar radiation or future loading on the recent storm may cause another cycle of natural activity, or an increased sensitivity to human triggers. There are older weak layers that are now buried down around 60-80 cms and also at about 110 cms. These layers have been unlikely to trigger by skiers, but they may still be sensitive to large loads like avalanches in motion or cornice fall.

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