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Avalanche Forecast

Archived

Dec 22nd, 2024–Dec 23rd, 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, East Purcell, West Purcell.

Choose sheltered, low-consequence terrain. Recently formed wind slabs along with a chance of buried weak layers necessitate a conservative approach.

Confidence

Moderate

Avalanche Summary

Multiple wind slab avalanches were reported on Saturday up to size 1.5, both skier and explosive triggered. All these avalanches occurred in alpine terrain, primarily on north-facing terrain.

Snowpack Summary

10 to 20 cm of recent snow has been redistributed in deeper deposits in lee-facing terrain at higher elevations due to southwest winds.

The mid-snowpack may hold a weak surface hoar or facets layer on shaded slopes and a sun crust on south-facing slopes, buried 30 to 60 cm deep.

Near Invermere, the snowpack base is weak, with faceted snow over an October crust. This layer likely exists region-wide but has only shown signs of instability near Invermere.

Weather Summary

Sunday Night

Mostly cloudy with 0 to 2 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -7 °C.

Monday

Mostly cloudy with 0 to 2 cm of snow. 10 to 30 km/h southwest ridgetop wind. Treeline temperature -7 °C.

Tuesday

Partly cloudy with 0 to 2 cm of snow. 10 to 30 km/h southwest ridgetop wind. Treeline temperature -7 °C.

Wednesday

Mix of sun and cloud. 10 to 30 km/h southwest ridgetop wind. Treeline temperature -7 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful as you transition into wind-affected terrain.
  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.