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Avalanche Forecast

Archived

Nov 18th, 2024–Nov 19th, 2024

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

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Wind slabs remain the primary avalanche concern. Wind and new snow on Sunday created wind slabs at upper elevations that are still possible to trigger. Though small in size, these slabs could pose serious consequences if triggered in the wrong terrain.

Not much snow at the lower levels of treeline or below; it is Early Season!

Confidence

Moderate

Avalanche Summary

Local ski hills were able to trigger wind slabs as well as slabs on the basal crust from size 1-1.5 with explosives on Monday.

On Sunday local ski hills reported several small windslabs and a recreational party reported a remotely triggered wind slab while ascending a couloir near Bow Summit.

Our field team reported numerous whumpfs while touring in the Sunshine area on Monday. These are likely failing on one of the buried crusts in the snowpack.

Snowpack Summary

A few cms of snow over previous wind slabs in exposed alpine and treeline terrain. In the middle of the snowpack the Nov 9 solar/temp crust is present. In some places there is surface hoar on this crust making it more reactive to loading. At the base of the snowpack a crust that formed in late October can be found to ridgetop. Facets are developing around this basal crust. Treeline snow depths range from 40-60 cm with less snow at lower elevations and many thinly buried hazards.

Weather Summary

A mix of sun and cloud with no new snow on Tuesday and only a few cm's expected on Wednesday. Winds remain light from the SW on Tuesday until late in the afternoon when they increase to the moderate-strong range from the south. A cooling trend continues, with forecast lows reaching -20°C in the alpine.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.