Avalanche forecast

Kootenay Boundary

Jan 14 – 15, 2022Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

 Dial back your exposure to avalanche terrain when temperatures increase. Large avalanches are possible as recent snow and buried weak layers adjust to the warming.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    A persistent slab problem formed by a crust down 120-200 cm has created a low likelihood, high consequence scenario that is difficult to forecast. The deeply buried weak layer has produced a number of large and surprising avalanches over the past two weeks. This problem is most likely to be triggered from thin or variable depth snowpack areas such as wind affected features, ridge crests, and near rocky outcroppings. The same feature or path can slide repeatedly when the persistent weak layer is reloaded with new snow.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    Be mindful around steep and convex openings in the trees and along ridge features where the recent snow could remain reactive to triggering. The storm snow may overlie a weak interface, which could result in wider and touchier slabs than expected.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

THURSDAY NIGHT: Partly cloudy, no precipitation, light wind from the northwest, treeline temperatures cool to -3 C with freezing level dropping below 1200 m.

FRIDAY: Mostly cloudy skies, no precipitation, light wind from the west, treeline and alpine temperatures around -2 C with freezing level around 1000 m.

SATURDAY: Cloudy with isolated flurries, up to 5 cm of new snow, moderate wind from the southwest, treeline temperatures around -2 C with freezing level around 1000 m.

SUNDAY: Mostly sunny skies, no precipitation, moderate wind from the west, treeline temperatures around -4 C.

Avalanche Summary

A widespread avalanche cycle occurred during Wednesday's warm storm. This included numerous size 1-2 avalanches and one size 3 avalanche on Ymir Mountain. These avalanches were 20-40 cm thick, and in many cases were suspected to have failed on a recently buried surface hoar layer (see photos in the MIN post). The storm slabs above this layer were also very reactive to human triggers, and will likely remain possible to trigger in the upcoming days.

We have not heard reports of persistent slab avalanches since last weekend, when we saw several size 2 to 3 avalanches releasing on the early December facet/crust layer. Prior to these avalanches, we were seeing a regular pattern of large destructive avalanches on this layer at the start of the month. These avalanches mostly occurred on thin, wind affected slopes near ridgetops. Although there has been a declining pattern in persistent slab activity, the current warm temperatures could be testing them and warrant some extra caution.

Snowpack Summary

10-30 cm of recent snow is settling with the mild temperatures, but could remain reactive as it sits above a layer of feathery surface hoar and melt-freeze crusts. Lower elevations will likely go through a daily melt-freeze cycle. An accumulated total of 70-100 cm of snow since the beginning of January sits over variable and potentially weak snow surfaces including widespread facets and/or surface hoar up to 5 mm in sheltered areas.

The early December crust/facet layer has been responsible for sporadic but very large, persistent slab avalanches over the past month. The crust is now buried 120-200 cm deep except in thin, wind affected areas near ridgetops where most of the recent avalanches have been triggered.

Terrain and Travel

  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

Regions covered