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Avalanche Forecast

Archived

Nov 23rd, 2022–Nov 24th, 2022

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

Regions

Glacier.

Fresh windslabs are building over recently buried surface hoar, facets, and sun crust. Expect the new snow to be sensitive to human triggering in exposed lee terrain.

Knee tweaking and bone-snapping hazards may be buried just below the surface of the early season snowpack, travel with caution.

Confidence

Moderate

Avalanche Summary

Expect windslabs to become reactive in exposed terrain with the strong SW winds forecast for Thursday.

There were a few small slab avalanches in the steep terrain east of Rogers Pass overnight into Wednesday - MacDonald Gully #9 size 2.0, Tupper Minor size 1.5, and Tractor Shed East size 1.5.

Snowpack Summary

SW winds will redistribute up to 20cm of recent snowfall, forming fresh windslabs. These overlie surface hoar (5-30mm), facets, and crust on solar aspects. The buried surface hoar is largest at and below treeline.

The early season snowpack is thin and variable, with an average depth of 60cm below treeline, 80cm at treeline, and up to 120cm in the alpine in loaded areas. These values are below threshold for burying hazards, covering creeks, and bridging crevasses.

Weather Summary

Gradually increasing temps and winds into Thursday, with alpine highs reaching -2*C, and Moderate to Strong SW ridgetop winds.

More snow begins early Friday (up to 15cm through the day) and continues through the weekend. Storm snow totals (Tuesday-Sunday) may reach 50cm by the end of the weekend.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

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.