Boletín de aludes

Northwest Coastal

Feb 6 – 7, 2022Avalanche Canada
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Archivado · caducó 5 years ago

Peligro de aludes

Tue
Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Lo esencial

With additional snow, wind, and warming on Sunday, triggering large avalanches in the recent snow remains likely. Given the complexity of weather inputs, it is critical to stay disciplined with terrain. 

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    40-60 cm of recent storm snow is settling rapidly over colder, weaker snow or getting redistributed by strong winds into reactive slabs. This problematic set-up means that avalanches in the recent snow will remain likely to trigger on Sunday, especially with new snow, wind, and warming temperatures adding additional load. Expect this problem to be more pronounced in wind-drifted areas. 

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Rising freezing levels may bring rain rather than snow at lower elevations. Wet loose avalanches may be widespread, especially from steeper slopes with an underlying crust. 

Confidence

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

Weather Forecast

Saturday night: Cloudy, 5-15 cm of snow, strong southwest wind with extreme gusts in the alpine, treeline temperatures dropping to -2 C, freezing level near 800 m.

Sunday: Cloudy, 5-10 cm of snow, strong southwest wind with extreme gusts in the alpine, treeline high temperature near 0 C, freezing level rising to 1200 m. 

Monday: Mainly cloudy, 20-35 cm of snow, moderate west winds increasing to strong in the alpine, treeline high temperature near -4 C, freezing level dropping to 800 m.

Tuesday: Cloudy, 15-35 cm of snow, strong southwest winds with extreme gusts in the alpine, treeline high temperatures near -1 C, freezing level rising to 1000 m. 

Avalanche Summary

Overnight on Saturday, there were reports of large to very large (size 2-3.5) wind slab avalanches releasing naturally, primarily in areas north in the region. Operators also reported the beginnings of a natural loose wet avalanche cycle at low elevations. 

Near Terrace, explosives continue to trigger large (size 2-2.5) avalanches. These avalanches have propagated widely across terrain and have likely failed on a weak layer from early February. 

Snowpack Summary

Since Wednesday, the mountains have picked up 20-35 cm of snow near Terrace and 40-65 cm in areas north in the region. In the last 24 hours, strong to extreme southwest winds have rapidly redistributed the recent snow into reactive slabs at upper elevations. 

The recent snow sits above a variety of surfaces, including a crust, sugary facets, and layer of feathery surface hoar (buried February 2nd). This particular storm interface continues to remain suspect as it is unlikely to bond well, and it has increased potential to produce avalanches that fracture widely across terrain. The crust can be found at or below treeline as well as on south-facing terrain in the alpine. Facets likely formed on colder aspects, and surface hoar may be found in isolated sheltered terrain at treeline. Below around 1200m, the upper snowpack is wet to moist over these surfaces.

Deeper in the snowpack, a surface hoar layer from mid-January may still be found down 70-100 cm at upper elevations in sheltered terrain. Recent reports indicate that it is becoming less of a concern.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Extra caution for areas experiencing rapidly warming temperatures for the first time.
  • In times of uncertainty conservative terrain choices are our best defense.

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