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Avalanche Forecast

Archived

Dec 2nd, 2024–Dec 3rd, 2024

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells, South Rockies, Akamina, East Purcell, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

The likelihood of deep persistent slab avalanches may increase with prolonged warm weather.

Avoid steep, wind-loaded slopes as this is where you're most likely to trigger an avalanche.

Confidence

Low

Avalanche Summary

In the past week, several size 1 to 1.5 deep persistent slab avalanches have been reported in the Invermere area. These 40 cm thick slabs are failing on weak basal snow and have been triggered by both riders and explosives.

No wind slab avalanches have been reported, though wind transport has been observed.

Snowpack Summary

Treeline snow depths are 50 to 70 cm, with deeper wind-loaded pockets in the alpine. Surface snow is being redistributed by wind in exposed areas but remains soft in sheltered terrain.

In the Invermere area, weak faceted snow at the base of the snowpack has caused several small but notable deep persistent slab avalanches. Similar conditions are likely in the South Rockies, though observations are limited.

Weather Summary

Monday Night

Mainly clear. 10 to 15 km/h southwest ridge top wind. Treeline temperature 1 °C

Tuesday

Mainly clear. 20 to 30 km/h southwest ridge top winds. Treeline temperature 1 °C.

Wednesday

Mainly clear. 20 to 30 km/h southwest ridge top wind. Treeline temperature 2 °C.

Thursday

Mainly Clear. 20 to 40 km/h southwest ridge top wind. Treeline temperature 1 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • 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.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.