Avalanche forecast

Northwest Inland

Nov 24, 2017Avalanche Canada
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Avalanche danger

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

A complex snowpack has begun to take shape in the Northwest. Choose terrain that is unlikely to release a storm slab and you'll likely avoid triggering the more dangerous persistent slab lurking beneath it.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Recent stormy weather has been building touchy storm slabs. The problem is widespread but you can expect slabs to be especially reactive in wind affected areas with more variable snow distribution

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3
    A crust that formed in October exists near the base of the snowpack and a layer of weak, sugary snow has developed above it. This layer may react to a heavy trigger such as a storm slab release. This would produce a very large, destructive avalanche.

Confidence

Low - Due to the number of field observations

Weather Forecast

Friday: Mainly cloudy with scattered flurries and a trace to 5 cm of new snow. Moderate to strong southwest winds. Alpine temperatures around -5.Saturday: Mainly cloudy with scattered flurries and a approximately 5 cm of new snow. Moderate south winds. Alpine temperatures around -4.Sunday: Cloudy with isolated flurries and a trace to 5 cm of new snow. Moderate south winds. Alpine temperatures of -3.

Avalanche Summary

One report from Wednesday discussed several estimated Size 2.5-3 avalanches observed on the Kathlyn face of Hudson Bay Mountain. No other new avalanches have been reported, which almost certainly owes more to a lack of observers than a lack of avalanche activity and potential. Please post your observations to the Mountain Information Network. (MIN)

Snowpack Summary

Snowpack depths over the region are above average for late November, with approximately 150 cm of settled snow present at treeline elevations and above. Stormy weather over the mid-week delivered about 30 cm of new snow to the region, forming storm slabs which are expected to be particularly reactive in open terrain where wind effects promote more variable loading. Mid-treeline and lower elevations did receive some precipitation as rain toward the end of the storm, but his thin rain layer is not expected to offer much bridging strength to the snowpack. About 20-30 cm of recent storm snow lies below this week's accumulations and above the widespread late October crust. The October crust is present near the base of the snowpack at all elevations and features a layer of weak, sugary grains above it. This "crust/facet combo" layer remains an ongoing concern for step-down potential from large triggers such as a storm slab release. The crust is less of a concern below treeline where it is broken up by vegetation near the ground.

Regions covered