Lawinenlagebericht

Kootenay Boundary

Feb 18 – 19, 2022Avalanche Canada
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Lawinengefahr

Sun
Mon
Hochgebirge
1 · Gering
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Heightened avalanche conditions exist on open convex slopes. Avalanches are less likely where thick crusts exist near the surface.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    1.5–2.5

    Persistent slab avalanches are possible on shaded aspects due to two buried layers of surface hoar. These layers are 20 to 50 cm deep and exist with various combinations of crusts above and below them, which has made the distribution of this problem spotty. The problem is less likely in areas with thick and supportive crusts near the surface, but you should be cautious on steep open slopes at treeline, especially in terrain where surface hoar is more likely to be preserved - like cut blocks.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

THURSDAY NIGHT: Cloudy skies, no significant precipitation, moderate wind from the northwest, treeline temperatures around -5 C.

FRIDAY: Cloudy skies, no significant precipitation, moderate wind from the west, treeline temperatures around -4 C with freezing level around 1200 m.

SATURDAY: Cloudy with flurries bringing 5-15 cm of snow by the evening, moderate wind from the southwest, treeline temperatures around -6 C.

SUNDAY: Another 5-10 cm of snow by the morning then clearing throughout the day with a mix of sun and cloud, light wind from the northwest, treeline temperatures drop from -5 to -10 C throughout the day.

Avalanche Summary

Most avalanche activity over the past few days has been small (size 1) human-triggered wind slabs along ridgetops and some small dry loose avalanches. Last week there were several large (size 2-3) persistent slab avalanches reported on the late January surface hoar layer, and this layer produced a few smaller (size 1) human-triggered slabs as recently as Tuesday.

Snowpack Summary

5 to 10 cm of fresh snow sits above hard wind-affect snow and melt-freeze crusts in most terrain. The exception could be north-facing terrain at treeline where there may still be soft snow. There are two layers of buried surface hoar in the upper snowpack: one was buried at the end of January and is 20 to 40 cm deep, the other was buried in the middle of January and is 30 to 50 cm deep. These layers remain reactive in some snowpack tests and resulted in avalanche activity over the past week. Triggering avalanches on this layer has become less likely in the past few days, but may still be possible on sheltered northerly slopes. The lower snowpack is well consolidated, with a crust/facet layer found 100 to 200 cm deep. This layer is currently considered dormant, but could become active later this season as discussed in this forecaster blog.

Terrain and Travel

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Pay attention to isolated alpine features as well as cross-loaded features at treeline.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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