Avalanche forecast

South Rockies

Mar 24 – 25, 2014Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Cornices in the region are now very large and fragile. A cornice fall could be destructive by itself, and could trigger a large avalanche on the slope below.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    This problem may become more sensitive if temperatures rise as forecast on Tuesday. Be particularly cautious in wind-loaded and cross-loaded terrain.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    The deep weak layers that formed in early February may be a bit touchier in the north of the region. Possible triggers at this point include a large cornice fall, surface avalanche in motion or solar warming.

Confidence

Fair - Freezing levels are uncertain on Tuesday

Weather Forecast

Tuesday: Mainly cloudy with possible showers or flurries. The freezing level should climb to around 2000 m (or a little higher). Ridge winds are light to moderate from the SW. Wednesday: Periods of snow 10-20 cm. The freezing level is around 1000-1200 m and ridge winds are light to moderate from the SW. Thursday: Cloudy with flurries. The freezing level is around 1200 m and ridge winds are light.

Avalanche Summary

Recent activity has been limited to loose dry or loose wet sluffing in steep terrain and a few skier and explosive controlled slab avalanches up to size 2. These recent slabs only involved the storm snow and were around 20-30 cm deep on average.

Snowpack Summary

The region picked up 5 - 10cm of convective snowfall Saturday night which adds to the 60 - 100 cm of storm snow fell in the last week. Winds have been out of the SW through NW which has created fresh wind slabs in lee terrain. Around 70 cm of settling storm snow rests on a graupel layer that can be found in much of the region. This makes for around 90 cm on top of the mid march crust at this point. This crust exists on all aspects below 2000m and on solar aspects in the high alpine. North of Sparwood and in the Crowsnest Pass area, the buried crust seems more specific to previously sun-exposed slopes. The deep mid-February facet/crust persistent weakness, now down up to 150cm, seems unlikely to trigger in areas where the hard, supportive crust exists. No matter where you are in the region, this weakness should stay on your radar as any activity at this interface would be large and destructive. Possible triggers include a large cornice fall, a large input in a thin snowpack area or solar warming. Cornices are also large and unstable.See this great video from our South Rockies field team that does an awesome job of summarizing the current state of the snowpack.

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