Lawinenlagebericht

Kootenay Boundary

Mar 25 – 26, 2022Avalanche Canada
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Lawinengefahr

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

 Be thoughtful with your terrain choices, and pay attention to how the weather is affecting the snowpack through the day. Natural and human triggered avalanches are possible on steep slopes that are baking in the sun. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    1.5–3

    This layer is getting harder for riders to trigger, but it is possible that it could still produce large, surprising avalanches. Triggering may be more likely when temperatures are above zero, or when they rapidly change in either direction.

    This layer is a concern where there is a poor bond to underlying surface hoar crystals. This problem seems most pronounced in the Selkirks around Nelson and Kootenay Pass.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Temperatures are forecasted to stay quite steady overnight, and the surface snow may not solidly refreeze at lower elevations. Pay close attention to how thick and supportive the surface crust is throughout the day, and avoid steep slopes when they are baking in the sun. This will help you avoid wet loose avalanche problems. 

Confidence

Moderate - The snowpack structure is generally well understood. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

FRIDAY NIGHT: Mostly clear. No new snow/rain expected. Light southwest ridgetop winds. Freezing level holding around 2000 m with possible pockets of colder air in valley bottoms. 

SATURDAY: Mostly cloudy in the morning, sunny in the afternoon. No new snow/rain expected. Light southwest ridgetop wind. Freezing level rising to around 2200 m. 

SUNDAY: Partly cloudy. No new snow/rain expected. Light south ridgetop wind, trending to strong southwest at higher elevations. Freezing level rising to around 2700 m. 

MONDAY: Mostly cloudy. Very light rain overnight and through the day, possible snow at high elevations. Light to moderate southwest ridgetop wind. Freezing level around 2200 m. 

Avalanche Summary

On Wednesday and overnight into Thursday, (when temperatures were the warmest, and then cooled off rapidly), a few large (size 3) naturally triggered avalanches were reported. These avalanches:

  • were on aspects that were more likely to have preserved, buried surface hoar (NW,N,NE)
  • started in terrain around treeline or in the low alpine.
  • Failed on layers 50-100 cm deep that may have been buried between late January, and early March.
  • may have started as smaller avalanches that stepped down to deeper layers. 
  • occurred on the Selkirk (east) side of the region, like the similar avalanches that occurred earlier in the week.

This layer may prove to be less active on Friday and Saturday, but high temperatures on Sunday may wake them up again.

On Tuesday and Wednesday, widespread, loose wet avalanches were reported due to warm temperatures and/or sunshine (size 1-2). 

Snowpack Summary

Recent snow and moderate wind have formed small pockets of windslab in the high alpine. Refrozen crust on all aspects as high as 2500 m, softening in the afternoon at low elevations and on steep, sunny slopes. Recent warm temperatures, sun, and rain have made the top 10-30 cm of the snowpack moist. At very low elevations, the snowpack may be wet and isothermal, depending on overnight freezing levels. 

40 to 70 cm below the snow surface, you'll find a frozen sun crust on solar aspects, and weak, feathery surface hoar crystals on shaded aspects. This layer was buried in early March. During the last storm, and on the warmest days earlier this week, it produced surprising avalanches in the Selkirks (east side of the region). The recent warm weather may help this layer bond in the long run, but it's not yet time to take it out of your danger assessment for the day.

The mid and lower snowpack are generally strong and well bonded.

Terrain and Travel

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Be alert to conditions that change with aspect and elevation.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.

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