Avalanche forecast

Northwest Coastal

Dec 13 – 14, 2022Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

While pushing into bigger terrain be cautious of cohesive, wind slabs that may not be bonding well to the underlying surfaces.

Be especially cautious around treeline elevations where the recent snow is more likely to sit on top of a weak layer of preserved surface hoar.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    20 - 30 cm of storm snow now sits atop a preserved layer of surface hoar. In alpine and treeline terrain that has been exposed to more wind, surface snow may be redistributed into wind slabs. These wind slabs have the potential to scrub down to a buried surface hoar layer making for larger then expected avalanches. This is especially relevant at treeline elevations where the surface hoar is likely larger and better preserved.

Confidence

Moderate

Avalanche Summary

A couple of recent natural wind slabs in alpine terrain were observed on Sunday, up to size 2. A few reports over the weekend of sluffing or loose dry avalanches occurring in steep terrain that has been sheltered from the wind.

If you head out in the backcountry please support your community by submitting a MIN report!

Snowpack Summary

30 to 50cm of storm snow has been redistributed at higher elevations by variable winds, creating isolated pockets of wind slab on all aspects. This recent snow overlies a layer of surface hoar (buried in early December), sized 5-10 mm.

A layer that was buried in mid-November can be found down 80 to 120cm deep at treeline and above. This layer consists of a crust below 1200 m and a layer of surface hoar above this elevation. This layer has not shown any recent signs of instability.

In the alpine snowpack depths over 2 meters have been reported but the snowpack below treeline is still generally quite shallow.

Weather Summary

Monday Night

Cloudy skies with up to 10 cm of snow are forecast (values higher in the north of the region) overnight and into to Tuesday morning. Light to moderate westerly winds in the lower alpine, with potential for strong outflow winds through the coastal inlets.

Tuesday

Cloudy with snowfall tapering in the early morning and scattered flurries expected throughout the day. Light to moderate southwest winds, while outflow winds continue through inlets. Alpine temperatures in the -5 to -10 C range.

Wednesday

A mix of sun and cloud with isolated flurries throughout the region. Outflow winds continue. Light to moderate winds and temperatures in the -5 to -10 C range continues.

Thursday

A mix of sun and cloud. No precipitation forecast. Generally light alpine winds. with the potential for an alpine temperature inversion, where alpine highs of above freezing are possible.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Watch for areas of hard wind slab on alpine features.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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