Avalanche forecast

Purcells

Jan 20 – 21, 2024Avalanche Canada
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Avalanche danger

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

Fresh wind slabs at higher elevations can be found on all aspects. Expect as temperatures warm, that human triggered avalanches will become likely.

Avalanche problems

  • Wind Slabs

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

    Wind slabs may be more reactive where they sit on a weak layer of facets. Expect slab sensitivity to triggering and reactivity to increase as temperatures warm.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1.5–3.5

    There is a weak layer of facets and depth hoar near the base of the snowpack in most alpine areas. The likelihood of triggering a deep persistent slab is low, however the consequence of doing so is high.

Confidence

Moderate

Avalanche Summary

On Thursday explosive avalanche control missions triggered a very large avalanche size 3.5. This avalanche failed on the deep persistent slab layer and was 100 to 250 cm in slab depth, running over 500 meters in length. Earlier in the week natural and explosives triggered wind slab and loose dry avalanches were reported to size 1 and 1.5.

If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).

Snowpack Summary

5-10 cm of low density new snow is sitting on weak faceted snow in many areas. In exposed terrain at treeline and above, this new snow is now obscuring old wind slabs.

The mid and lower snowpack is generally weak with several layers of note. Of greatest concern are weak facets and/or depth hoar located at the bottom of the snowpack, particularly in alpine terrain.

Snowpack depths at treeline range from 70 to 160 cm.

Weather Summary

Friday Night

Mainly cloudy with isolated flurries, 1-2 cm of snow, southwest ridgetop wind 10 to 30 km/h, treeline temperature -14 °C.

Saturday

Mainly cloudy with isolated flurries, 1-2 cm of snow, west ridgetop wind 20 to 40 km/h, treeline temperature -15 °C.

Sunday

Mainly cloudy with flurries, 2-4 cm of snow, southwest ridgetop wind 10 to 30 km/h, treeline temperature -10 °C.

Monday

Mainly cloudy with flurries, 2-4 cm of snow, southwest ridgetop wind 10 to 30 km/h, treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Regions covered