Avalanche forecast

Kootenay Boundary

Feb 21 – 22, 2020Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

One more day of full sun before a stormier weekend. Use added caution on steep slopes in open trees, as the snow may rest on surface hoar, particularly around Kootenay Pass. You may also find lingering slabs in wind-loaded features at higher elevations.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    A 20 to 30 cm slab has been reactive to riders in the past few days. The slab has been touchiest in open trees around Kootenay Pass, where it rests on a layer of weak and feathery surface hoar. The spatial distribution of the surface hoar layer is unclear and may be spottier in the remainder of the region. Near ridge lines, the slab has been touchiest in lee terrain features due to recent wind transportation.

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

THURSDAY NIGHT: Clear skies, light to moderate southwest wind, alpine temperature -5 C.

FRIDAY: Clear skies, light to moderate southwest wind, alpine temperature -5 C, freezing level 1300 m.

SATURDAY: Mix of sun and cloud with isolated flurries, accumulation 1 to 3 cm, light to moderate southwest wind, alpine temperature -5 C, freezing level 1000 m.

SUNDAY: Increasing cloud with afternoon snowfall, accumulation 5 cm, moderate southwest wind, alpine temperature -6 C, freezing level 1000 m.

Avalanche Summary

On Wednesday, a few storm slab avalanches were triggered by explosives. They were on northerly aspects and around 30 cm deep. On Tuesday, a few storm slab avalanches released around Kootenay Pass on the surface hoar layer described in the Snowpack Summary. There are great photos and descriptions of these avalanches on the MIN, summarized here.

Snowpack Summary

A 20 to 30 cm thick slab has been reactive to human traffic in the past few days, particularly around Kootenay Pass. The slab may overly a weak layer of feathery surface hoar crystals in open trees. In the alpine near ridges, the slab has been most reactive on north to east to south aspects due to recent wind transportation. On south aspects, sunny skies have melted the surface snow, which may be wet during the daytime heat and freeze into a melt-freeze crust during the night.

A few other crusts exist in the top 100 cm of the snowpack; reports suggest that the overlying snow is bonding well to them.

Terrain and Travel

  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.

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