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Avalanche Forecast

Archived

Nov 25th, 2024–Nov 26th, 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 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.

Regions

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

Rider triggered slab avalanches are sliding on a buried crust near the base of the snowpack.

Start conservative and watch for signs of instability like cracking or whumpfing.

Confidence

Low

Avalanche Summary

Over the weekend, numerous natural and human-triggered persistent slab avalanches (up to size 2.5) were observed near Invermere. These primarily occurred on north through southeast aspects at treeline and above. Smaller wind slab avalanches could step-down to the basal facets, initiating a larger slab avalanche.

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

Snowpack Summary

10 to 15 cm of new snow fell over the weekend. In wind-exposed areas cracking and whumping have been reported.

Down 40 to 50 cm sits a layer of surface hoar primarily found on shaded slopes, or on a thin crust on sunny slopes.

A crust exists near the bottom of the snowpack. This crust may have weak, sugary facets on top.

Snowpack depths are reported to be 50-70 cm at treeline elevation.

Weather Summary

Monday Night

Mostly cloudy with 2 to 5 cm of snow. 15 to 30 km/h west ridgetop wind. Treeline temperature -10 °C.

Tuesday

Cloudy with some clear periods. 15 to 20 km/h northwest ridgetop wind. Treeline temperature -10 °C.

Wednesday

A mix of sun and cloud, no new snow. 15 to 20 km/h northwest ridgetop wind. Treeline temperature -14 °C.

Thursday

A mix of sun and cloud. 10 km/h west ridgetop wind. Treeline temperature -15 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

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.