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Avalanche Forecast

Archived

Nov 24th, 2024–Nov 25th, 2024

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

Regions

Purcells, South Rockies, East Purcell, Bull, Elkford East, Elkford West.

Recent snowfall is adding to the load on a buried weak layer.

Choose conservative routes and be mindful of wind-loaded slopes.

Confidence

Low

Avalanche Summary

Several large (up to size 2.5) natural and human-triggered persistent slab avalanches were observed near Invermere on Saturday. Mostly northwest, through north, to east aspects at all elevations.

On Friday, a skier triggered a large (size 2) persistent slab avalanche near Invermere. It occurred at treeline, on a steep slope.

Information is very limited at the moment. Please consider submitting a MIN.

Snowpack Summary

40-50 cm of soft snow sits on a layer of surface hoar on shaded slopes, or a thin crust on sunny slopes.

There is a crust from early November at the base of the snowpack. The crust may have weak, sugary facets on top, if this is the case large avalanches are possible. Snowpack depths are expected to be 50-70 cm at treeline.

Weather Summary

Sunday Night

Mostly cloudy with up to 5 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -9 °C.

Monday

Mostly cloudy with 5 to 10 cm of snow. 20 to 40 km/h southwest ridgetop wind. Treeline temperature -7 °C.

Tuesday

A mix of sun and cloud, clearing, no new snow. 20 to 30 km/h west ridgetop wind. Treeline temperature -8 °C.

Wednesday

A mix of sun and cloud with 1 cm of snow. 20 to 30 km/h west ridgetop wind. Treeline temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Choose simple, low-angle terrain without steep convex rolls.
  • Make observations and continually assess conditions as you travel.
  • Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.
  • Recent wind has varied in direction, so watch for wind slabs on all aspects.

Problems

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.

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.