Avalanche forecast

Purcells

Nov 29 – 30, 2024Avalanche Canada
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Avalanche danger

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

Weak layers in the snowpack warrant careful terrain choices and watching for signs signs of instability like cracking or whumpfing.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Recent westerly winds may have formed wind slabs along ridgelines and in exposed terrain.

  • Deep Persistent Slabs

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

    Deep persistent slab avalanches have recently failed on weak faceted snow at the base of the snowpack. This problem is most likely found in the alpine and at treeline on smooth slopes.

Confidence

Low

Avalanche Summary

A size 1 deep persistent slab, 30–40 cm thick, was human-triggered below treeline on Tuesday. Last weekend, several natural and human-triggered slab avalanches (size 1 to 2) occurred near Invermere, mainly on north aspects. These avalanches failed on weak facets near the base of the snowpack.

Observations from the South Rockies are limited.

Smaller wind slab avalanches could step down to basal facets, triggering larger avalanches.

Snowpack Summary

Up to 15 cm of new snow fell over the weekend. A surface hoar layer, 30 to 40 cm deep, is present on shaded slopes and atop a thin crust on sunny slopes. Near the base of the snowpack, a crust with weak sugary facets above and below caused large avalanches last weekend. Snowpack depths at treeline range from 50 to 70 cm.

Most observations are from the Invermere area, but similar conditions are likely in the South Rockies.

Weather Summary

Thursday Night

Mostly cloudy. 10 to 30 km/h west ridgetop wind. Treeline temperature -12 °C.

Friday

Mostly cloudy with up to 1 cm of snow. 30 to 40 km/h west ridgetop wind. Treeline temperature -10 °C.

Saturday

Mix of sun and cloud. 30 km/h west ridgetop wind. Treeline temperature -8 °C.

Sunday

Mostly cloudy with up to 1 cm of snow. 30 km/h west ridgetop wind. Treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep terrain, including convex rolls, or areas with a thin, rocky, or variable snowpack.
  • Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.

Regions covered