Avalanche forecast

Northwest Inland

Dec 27 – 28, 2016Avalanche Canada
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Avalanche danger

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

Tricky snowpack conditions exist and require a conservative and cautious approach to terrain, especially if you see signs of recent loading.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Expect fresh wind slabs as strong westerly winds redistribute the new snow. Wind slabs may also be burying a layer of surface hoar that could make them extra touchy.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–3
    40-60 cm of recent snow sits above a weak, faceted lower snowpack. Triggering persistent slabs will become more likely with loading from new snow and wind. Likely trigger points are unsupported slopes in shallower snowpack areas.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

WEDNESDAY: Flurries with accumulations up to 10 cm, 40-60 km/h southwest winds, temperatures around -8C.THURSDAY: Flurries with 5-10 cm accumulations, 20-40 km/h northwest winds, temperatures around -8C.FRIDAY: Cloudy with isolated flurries, 60-80 km/h northwest winds, temperatures around -10C.

Avalanche Summary

On Monday, a skier remote triggered a size 1.5 wind slab in the Hankin area on a north aspect at treeline (see MIN report). They also reported a whumpfing caused by collapsing facets at the bottom of the snowpack. Over the weekend, numerous size 1.5-2 avalanches were remote triggered in the northern parts of the region, also releasing on weak facets near the ground.Wind slabs will remain touchy throughout the week, as sustained winds will redistribute the new low density snow. The additional load of new snow will also keep deeper persistent weak layers reactive, making it possible to trigger larger avalanches.

Snowpack Summary

Moderate to strong winds are redistributing 10-30 cm of low density storm snow and forming touchy wind slabs in the lee of exposed ridges. The new snow has also buried a layer of feathery surface hoar (up to 15 mm in sheltered areas), making wide propagations possible. A weak interface that formed during the early December cold snap can be found about 40-60 cm deep underneath a hard wind slab. The layer consists of weak faceted (sugary) snow, and preserved surface hoar in sheltered areas. The snowpack is still shallow throughout the region and widespread faceting of the lower snowpack is likely in most areas. A thick rain crust that formed in early November is probably near the bottom of the snowpack and is likely surrounded by sugary facets. Basal facets and depth hoar (more sugary crystals) right at the bottom of the snowpack are reportedly widespread.

Regions covered