Lawinenlagebericht

Northwest Coastal

Feb 22 – 23, 2020Avalanche Canada
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Lawinengefahr

Mon
Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Storm slabs are expected to be reactive to human traffic for a few days. A conservative mindset will be crucial until the snow stabilizes.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    Storm slabs are 30 to 50 cm thick and may take some time to bond to underlying surfaces. All this recent snow may rest on a weak layer of surface hoar in sheltered terrain such as open trees, and it may not bond well to a melt-freeze crust on sun-exposed aspects. The deepest deposits will likely be in lee terrain features near ridges, as the snow fell with strong south to west wind.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall and periods of clearing, accumulation 5 to 10 cm, moderate to strong west wind, alpine temperature -7 C.

SATURDAY: Mostly cloudy with light snowfall, accumulation 5 to 10 cm, strong west wind, alpine temperature -7 C, freezing level 700 m.

SUNDAY: Mostly cloudy with light snowfall, accumulation 2 to 5 cm, moderate south wind, alpine temperature -7 C, freezing level 500 m.

MONDAY: Mix of sun and cloud, light northwest wind, alpine temperature -10 C, freezing level valley bottom.

Avalanche Summary

A widespread natural storm slab cycle occurred in the region Thursday night into Friday during the storm. Riders reported many easy-to-trigger storm slabs, releasing on the surface hoar described in the Snowpack Summary. The slabs were 30 to 50 cm deep and on northerly aspects.

Snowpack Summary

Around 30 to 50 cm of snow accumulated from Thursday night to Friday and around 10 cm more is expected Friday night. This snow has likely formed storm slabs at all elevations. The slabs are likely deepest in lee terrain features, as the snow fell with strong south to west wind.

These slabs may slide easily where they overly a couple layers of surface hoar that may be found in sheltered terrain at and below treeline or a melt-freeze crust on sun-exposed aspects. You may find these layers around 50 and 80 cm deep.

A thin layer of weak and sugary faceted grains that formed in January may be found about 120 to 170 cm deep, and an early-season melt-freeze crust lingers at the base of the snowpack. These layers produced a few large natural avalanches in early-February but have recently been unreactive.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Choose conservative terrain and watch for clues of instability.

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