Lawinenlagebericht

Kootenay Boundary

Feb 15 – 16, 2022Avalanche Canada
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Lawinengefahr

Thu
Fri
Hochgebirge
1 · Gering
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Don't rely on surface conditions for clues to where the tricky persistent problem still exists. Open slopes at treeline are the most concerning, where buried surface hoar may be preserved. 

Whumpfing, shooting cracks and recent avalanches are clear signs of an unstable snowpack. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5
    • A layer of surface hoar from late January is buried 20-50 cm deep. On solar aspects and at lower elevations surface hoar sits over a melt freeze crust. 
    • Another layer of surface hoar/facets over a crust from early January is buried 40-120 cm deep. 

    Treat sheltered open slopes at a treeline with extra caution where the surface hoar is most likely to be preserved - like cut blocks. Deeper instabilities could be triggered in shallow snow pack areas or by a large load such as a cornice or step down avalanche. 

    Avalanche activity is less likely where a thick and supportive crust sits on the surface. 

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

The cold front moves out of the region tonight, light flurries continue Tuesday. A high pressure system builds Wednesday, bringing mostly dry conditions and scattered cloud.

MONDAY NIGHT: Mainly cloudy with flurries, trace to 3 cm overnight. Light to moderate north/nor'west winds and freezing levels around 500 m.

TUESDAY: Chance of flurries with moderate nor'west winds strengthening over the day. A mix of sun and cloud with freezing levels reaching 1500m. Alpine high -2. 

WEDNESDAY: A mix of sun and cloudy with isolated flurries. Moderate nor'west winds, freezing levels reach 1500m, alpine high of -2. 

THURSDAY: A mix of and cloud. Strong nor'west winds. Freezing levels rise toward 2000 m over the day. Alpine high of +2. 

Avalanche Summary

Last weeks warming trend and sun produced naturally triggered loose wet avalanches to size 2. 

As expected, persistent slab avalanche activity also increased as a result of the warmer temperatures. Size 1 - 3 slab avalanches were naturally and human triggered over the last week, on the late January surface hoar layer. Activity occurred on all aspects at treeline elevations.

Snowpack Summary

Exposed terrain at alpine and treeline elevations holds dense wind effected surfaces from westerly winds. Sheltered areas and lower elevations have a widespread melt freeze crust and surface hoar.

The late January interface is buried 20-40 cm deep, and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine. Surface hoar sits above the crust in sheltered areas at treeline and below. This layer is still producing human triggered avalanches and propagation-likely test results. 

The mid January interface is buried 40-70 cm deep, and consists of a crust, facets, and surface hoar. The snowpack below is well consolidated, with the early December crust/facet persistent weak layer buried 100-200 cm deep. It is currently considered dormant. We expect this layer to become active later this season, check out the forecaster blog for more information.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Be alert to conditions that change with aspect and elevation.
  • Be careful as you transition into wind affected terrain.

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