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Avalanche Forecast

Dec 20th, 2024–Dec 21st, 2024
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: East Purcell, Purcells.

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

Confidence

Moderate

Avalanche Summary

After the storm on Wednesday, numerous natural storm and wind slab avalanches were observed throughout the region (size 1-2) that likely ran during the storm.

On Thursday, explosive control in the Invermere area produced two size 2 deep slab avalanches from east-facing treeline terrain.

Snowpack Summary

Up to 20 cm of recent snowfall accompanied by southwest winds created wind slabs and scoured surfaces at alpine and treeline elevations.

The mid-snowpack may hold a weak layer of surface hoar or facets on shaded slopes and a sun crust on south-facing slopes, buried 20–40 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

Friday Night

Cloudy with up to 1 cm of new snow. 10 to 30 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Saturday

A mix of sun and cloud with isolated flurries. 5 to 25 km/h southwest ridgetop wind. Treeline temperature -4 °C.

Sunday

A mix of sun and cloud with isolated flurries. 10 to 40 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Monday

Cloudy with up to 2 cm of new snow. 10 to 40 km/h southwest ridgetop wind. Treeline temperature -4 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • 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.

Avalanche Problems

Wind Slabs

Recently formed wind slabs may remain reactive to human triggering at upper elevations.

Wind slabs have the potential to step down to buried weak layers, resulting in larger-than-expected avalanches.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 1.5

Deep Persistent Slabs

In the Invermere area, weak faceted snow at the base of the snowpack remains a concern. Avalanches have occurred on steep, smooth north-facing slopes where the snowpack is shallow and weak.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2.5