Avalanche forecast

Northwest Inland

Mar 11 – 12, 2016Avalanche Canada
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Avalanche danger

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

Extra caution is required in wind loaded terrain on Friday.If you're out in the mountains, please send us your observations and help improve this bulletin.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    New snow combined with moderate winds have created fresh wind slabs in lee terrain near ridge crests and terrain breaks. Older hard wind slabs may also be lurking below the surface.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Isolated large avalanches failing on weak snow at the base of the snowpack remain a possibility. This is a greater concern during sunny breaks or with a heavy trigger like a falling cornice.

Confidence

Low - Due to the number of field observations

Weather Forecast

3-6cm of new snowfall is expected on Saturday with freezing levels around 1000m and strong alpine winds from the southeast. A mix of sun and cloud is expected for both Sunday and Monday with afternoon freezing levels around 1000m and light to moderate alpine winds from the southeast.

Avalanche Summary

On Thursday, a MIN report from Smithers (https://goo.gl/ssYcRw) describes a natural size 1.5 wind slab that released on a southeast aspect at 1600m and was 30cm thick. Natural activity was also heard but not observed from cliffy terrain in the south of the region. On Wednesday, a few natural wind slabs up to size 2.5 were observed in steep wind-loaded alpine terrain in the south of the region. There was also a large cornice fall that did not trigger a slab on the slope below. In the northern part of the region there were some reports of solar induced slabs to size 3 on south aspects, and natural cornice falls. One cornice fall triggered a size 4 avalanche that released on the ground and cleaned out an entire bowl. It was 1km wide and ran 1.5km.

Snowpack Summary

Roughly 20-40 cm of snow has fallen in the past week, with the highest accumulations occurring in the southwest of the region. Strong ridgetop winds have shifted the new snow into hard or soft wind slabs in exposed terrain, adding to an ongoing wind slab problem. A layer of surface hoar from early January can be found in isolated locations between 60 and 140 cm down. There hasn't been any activity reported on this layer for a couple of weeks now and it is becoming less of a concern. In shallower areas the snowpack sits on a weak base layer of facetted snow. Recently, this layer has been active in the north of the region, responsible for several large avalanches in unsupported alpine terrain.

Regions covered