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Avalanche Forecast

Archived

Dec 11th, 2023–Dec 12th, 2023

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

Regions

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

Wind slabs dominate the landscape. Natural avalanche activity has tapered off but lots of features appear prime for human triggering.

Confidence

Moderate

Avalanche Summary

Clear skies today revealed further evidence of the previous avalanche cycle up to size 3.0 mainly on N and E aspects in the Alpine. Natural avalanche activity has tapered, but human triggering is likely.

Snowpack Summary

Quite a change in our snowpack over the past 48hrs. Most ridges are back to being gravel or old snow and many treed areas have been blown clean. This has led to a new batch of wind slabs in most lee and cross-loaded areas. Many of the avalanches from the last couple of days have been filled in with only the debris deposits being visible. There's a good chance the crust from the last rain storm is exposed in wind prone areas. While the wind slabs are the main concern, don't forget the deeper layers are still players in the avalanche game. Dig down and keep track of the crust's location/condition/reactivity and remember, in some areas the early December surface hoar layer may still be intact. The snowpack is still very shallow and travel at lower elevations is challenging.

Weather Summary

Tuesday will bring mainly sunny skies and moderate to strong westerly winds. Temperatures will be mild with an above freezing layer possible between 1800 and 3000m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Approach lee and cross-loaded slopes with caution.

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.

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.