Avalanche forecast

South Coast

Mar 18 – 19, 2015Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Forecast snowfall amounts are uncertain. Pay close attention to how much snow falls in your area, and choose terrain accordingly.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    New snow and wind will form new wind slabs, and hide old wind slabs which exist on a variety of aspects. Watch for triggering in gullies and in the lee of ridge crests.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Reports of remote triggering from distances of up to 100m indicates that persistent slab avalanches should be on our radar. The buried crust/facet layer may be with us for a while, and could produce surprisingly large avalanches.

Confidence

Fair - Due to the number of field observations

Weather Forecast

A pacific storm will intensify on Wednesday night bringing generally light snowfall to the region for Thursday and Friday. A clearing trend is forecast for late Saturday. Up to 10cm of snow is forecast for Wednesday night and Thursday. Around 5cm of snow is expected on Friday. 5-10cm is forecast for Saturday. Ridgetop winds should remain strong from the southwest. Freezing levels are expected to hover around 1800m, although Friday may see a spike to about 2200m.

Avalanche Summary

A cycle of wind slabs and storm slabs (mostly size 1, up to size 2) was reported on Sunday and Monday. These failed naturally and were triggered remotely by skiers as well. Many were on north aspects. A snowmobiler also triggered an avalanche on Sunday in the Hurley area (check out the blue pin on our forecast map). On Wednesday, a size 2 slab avalanche was remotely triggered from a distance of 100m. The avalanche failed on a north aspect at 2050m between the Duffey Lake road and Gates Lake. This avalanche failed on the recently buried crust/facet combo, and speaks to the potentially touchy nature of the interface. New snow and wind on Thursday will likely spark a new new round of wind slab activity.

Snowpack Summary

Wind slabs and wind-affected surfaces are the main theme at the snow surface. New snow and wind on Thursday is expected to form new and reactive storm slabs. Cornices may also be fragile.  A crust/facet combo down 10-60 cm produces moderate, sudden results in snowpack tests. Avalanche problems associated with this layer may linger for a while, and may surprise with nasty consequences, especially in areas where the overlying slab is well-developed.  A second, deeper crust, marks the boundary with a lower snowpack that is reported to be generally well-settled and strong. Below treeline, the diminishing snowpack is trending isothermal (same temperature throughout).

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