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Avalanche Forecast

Archived

Dec 8th, 2022–Dec 9th, 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

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

We have a thinner snowpack than the last several years. Lot of early season hazards exist and there is a persistent weak layer that is giving us low confidence in the strength of the snowpack.

Confidence

Moderate

Avalanche Summary

A few small size 1 windslabs were triggered by snow safety teams in alpine terrain at Sunshine Village today. These were relatively easy to trigger but small in size. No other avalanches observed or reported on Thursday.

Snowpack Summary

5-30cm of snow and wind over the last few days has formed small but reactive wind slabs at higher elevations. These sit on several weak layers including the basal facets/surface hoar/sun crust combo which we are calling the Nov. 16th interface. Average snowpack depths at treeline are 60 to 100 cm throughout the region.

Weather Summary

Moderate to strong S/SW winds are decreasing to light to moderate overnight and into Friday. Alpine temperatures will remain cool in the -10 to -15 range and light flurries can be expected over the next few days with only light accumulation of 1-5 cm by Sunday.

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices at this time.
  • Approach lee and cross-loaded slopes with caution.

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.