Avalanche forecast

Kootenay Boundary

Mar 18 – 19, 2025Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Numerous large rider triggered avalanches continue to be reported in this region.

Triggering is most likely at treeline and above on wind-loaded slopes.

Avalanche problems

  • Persistent Slabs

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

    Several persistent weak layers exist in the upper metre of the snowpack. Small avalanches in motion may trigger these deeper layers creating very large and destructive avalanches.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Up to 60 cm of recent snow has formed reactive storm slabs. These slabs will be most reactive on wind-loaded slopes and on sunny slopes during periods of strong solar radiation.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–1.5

    Wet loose avalanches will become very likely when the sun comes out. Avoid overhead hazard from steep sunny slopes when the solar radiation is strong.

Confidence

Moderate

Avalanche Summary

On Monday, numerous skier triggered storm slab avalanches up to size 2 were reported primarily at treeline and above on a variety of aspects. Here's one example.

A snowcat triggered a size 2.5 persistent slab avalanche on the early March Surface hoar layer on a east aspect at treeline. The avalanche stepped-down 90 cm to the late January surface hoar layer.

A cornice fall also triggered a storm slab which triggered a size 2.5 persistent slab on the early March layer.

Snowpack Summary

40 to 65 cm of recent snow and southwest winds formed slabs reactive to human triggers.

Concern remains for triggering persistent slab avalanches. These layers include:

  • Facets/surface hoar/crust from early March buried 40-70 cm.

  • Facets/surface hoar/crust from mid-February buried 60-100 cm

  • Facets/surface hoar/crust from late January buried 100-160 cm.

The lower snowpack is well settled and strong.

Weather Summary

Tuesday Night

Clear skies, 10 to 20 km/h southwest ridgetop winds, treeline temperature -8 °C, freezing level valley bottom.

Wednesday

Mix of sun and cloud, 30 to 40 km/h south ridgetop winds, treeline temperature -5 °C, freezing level 1400 m.

Thursday

Cloudy with flurries, 5-10 cm snow, 20 to 30 km/h southwest ridgetop winds, treeline temperature -4 °C, freezing level 1500 m.

Friday

Snow, 10-20 cm, 30 to 40 km/h southwest ridgetop winds, treeline temperature -4 °C, freezing level 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.
  • Use small, low consequence slopes to test the bond of the new snow.
  • Be aware of the potential for larger than expected storm slabs due to buried surface hoar.
  • Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.

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