Avalanche forecast

Northwest Inland

Feb 16 – 17, 2016Avalanche Canada
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Avalanche danger

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

Storm slabs continue to develop at higher elevations and will be reactive to human-triggering on Wednesday. Conservative terrain choices remain critical.Use extra caution on steep south facing slopes in the afternoon if the sun is out in full force.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Storm slabs are expected to continue to develop in steep, higher elevation terrain in response to loading from new snow and wind Tuesday overnight.  Wind loaded features are likely to have the most reactive slabs.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Buried weak layers are still reactive in the snowpack, especially in the far north of region, and have the potential to produce very large avalanches. Thin spot triggering, cornice releases, and smaller avalanches all have the potential to step down.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Wednesday is expected to be dry and mainly cloudy with sunny breaks. Alpine winds are expected to be light to moderate from the southeast and freezing levels are forecast to be 800-1100m. The next storm pulse is expected to arrive Wednesday evening.  5-10cm is expected by Thursday afternoon.  Freezing levels are expected to be around 700m on Thursday with light to moderate southwest winds.  Light snowfall is expected to continue on Friday.

Avalanche Summary

On Monday, isolated wind slab avalanches up to size 1.5 were reported.  On Sunday, a ski cut produced a size 1 storm slab avalanche on an east aspect at 1400m elevation. The slab was 25cm thick. A small natural cycle was reported on Sunday up to size 2 and failing in the recent storm snow, mainly in the alpine. On Saturday, a natural size 1.5 wind slab avalanche was reported on a west aspect at 2200m elevation which was 20cm thick. Wind slabs are expected to be reactive to human-triggering on Wednesday. In the far north, deeply buried persistent weak layers may still be reactive to large triggers such as a small avalanche stepping down or a cornice failure.

Snowpack Summary

Up to 60cm of snow has accumulated over the past week and overlies a melt freeze crust which extends up to around 2000m elevation. This recent snow is reported to be bonding well to the crust. Moist snow was reported below 1100m on Sunday and wet snow below 800m. Recent wind has redistributed the surface snow at higher elevations forming wind slabs in leeward features. The early January surface hoar/facet layer is down around 1m+ and remains a concern for commercial operations. This layer seems the most reactive in the north of the region but may still be a concern in the south as well. Shallow snowpack areas in the east and north of the region may have a weak base layer of facetted snow on or just above the ground.

Regions covered