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Avalanche Forecast

Archived

Jan 20th, 2024–Jan 21st, 2024

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

Regions

South Rockies, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West.

Anticipate finding wind slabs on all aspects. It has begun to warm in the alpine, expect the likelihood of human triggered avalanches to increase.

Confidence

Moderate

Avalanche Summary

On Friday ski cutting and explosive control continued to produce small persistent slab avalanches. A notable small naturally trigger avalanche was observed in a backcountry location adjacent to the Castle ski area. There was an explosives triggered size 2 wind slab avalanche reported on Thursday in the southern portion of the region. This ran on facets buried in early January.

Snowpack Summary

Recent new snow has accumulated over faceted snow and/or previously wind-affected snow. Expect current south west wind to transport this new snow onto north aspect lee terrain. At treeline and below there is a weak layer of facets over a crust, down 40 to 80 cm. This layer was reactive to skier triggering primarily on east aspects between 1500 and 2000 m last week in the south of the region.

The mid and lower snowpack contains a series of crusts and faceted snow.

The height of snow at treeline is roughly 80 to 150 cm.

Weather Summary

Saturday Night

Mostly cloudy with isolated flurries, west alpine wind 20 to 50 km/h, treeline temperature -7 °C.

Sunday

Mostly cloudy with 1 to 2 cm of snow, southwest alpine wind 15 to 30 km/h, treeline temperature -1 °C.

Monday

Mostly cloudy with isolated flurries, southwest alpine wind 10 to 30 km/h, treeline temperature -1 °C.

Tuesday

Mostly cloudy with isolated flurries, southwest alpine wind 10 to 30 km/h, treeline temperature -1 °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.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.