Avalanche forecast

South Columbia

Feb 12 – 13, 2015Avalanche Canada
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Avalanche danger

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

Conditions vary across the region. In some places, there is still a real possibility of triggering a surprisingly large avalanche.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Wind slabs may be lurking on lee and cross-loaded features in the alpine. Cornices are weak with warm temperatures and may collapse.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Persistent slabs are most likely to be triggered from thin snowpack areas, or with large triggers like cornice fall or an avalanche stepping down.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Warm temperatures and drizzle have weakened the snowpack, especially at low elevations.

Avalanche Summary

Loose wet avalanches to size 2 were triggered naturally and by skiers on Wednesday. These occurred on steep faces that caught some sun and at low elevations where the snowpack is water-soaked. A size 2.5 persistent slab failed on a steep shallow rocky feature at 2500 m, approximately 1 m deep. Cornices also collapsed naturally and with explosives.

Weather Forecast

Temperatures are very warm (freezing level peaking near 2800 m) on Thursday and Friday, before cooling on Saturday with the passage of a cold front. Light precipitation is expected on Friday, followed by 5-10 mm precipitation on Saturday. This tapers to flurries on Sunday. Winds are light to moderate SW, changing to NW on Saturday as the front passes through.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Snowpack Summary

Recent storm snow appears to be settling and bonding with warm temperatures. SW winds have created areas of wind slab on some alpine lee features. Keep your eyes open for cornices, which may be sensitive to collapsing with the warm temperatures. The late-Jan crust/surface hoar layer, buried up to a metre deep, remains a key concern. Triggering this could produce a surprisingly large avalanche. The mid-January surface hoar is typically down 80-120cm and is most likely to be triggered from thin or rocky snowpack areas; or perhaps with a cornice fall, or an avalanche stepping down. The mid-December weak layer is down over 120cm, but is generally considered unreactive.

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