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Avalanche Forecast

Archived

Nov 29th, 2022–Nov 30th, 2022

Alpine
Natural avalanches possible, human triggered probable.
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

Glacier.

Investigate the snowpack and its layering before venturing into bigger terrain. Weak layers in the mid-pack are shallow enough to be triggered, and deep enough for those avalanches to be dangerous.

Confidence

Low

Avalanche Summary

One MIN report of 'whumpfing' and remote triggering several avalanches up to size 1.5, ~50cm deep, on moraine features below Glacier Crest. A Parks Canada field team experienced widespread 'whumpfing' at treeline and below in the Fidelity area.

A natural avalanche cycle occurred early Sunday morning with numerous avalanches in the size 1.5-2.5 range and a few up to size 3.0.

Snowpack Summary

Previous strong SW winds have built wind slabs in Alpine lee features. The Nov 17 persistent slab (surface hoar 5-30mm, facets, and crust) is down 60-80cm and largest at treeline and below.

The early season hazards are slowly being buried but remain a concern. The height of snow at treeline is ~140cm.

Weather Summary

A brief storm moves through the area Wed, followed by a return to cold, calm conditions.

Expect 5-10cm of snow Wed, an Alpine high of -11*C, and gusty, moderate SW ridge-top winds.

Thurs/Fri will see a return to -20*C temps, calm winds, and clearing skies.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

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.