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Avalanche Forecast

Archived

Dec 13th, 2023–Dec 14th, 2023

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

Regions

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

A few wind triggered avalanches occurred on Wednesday. The basal snowpack layer remains weak and untrustworthy. Conservative route choices are still advised.

Confidence

Moderate

Avalanche Summary

A few wind triggered avalanches up to size 2 were observed Wednesday above Pilsner Pillar ice climb and in extreme terrain in Chickadee Valley. There have been more reports with the good visibility of avalanches up to size 2.5 that occurred after last weeks storm. Most originated in the alpine but some originated in treeline locations. On Saturday a size 2 skier triggered avalanche failed as a deep persistent slab at treeline and ran 600m scrubbing to ground.

Snowpack Summary

Wind affect in the alpine from Wednesdays strong SW winds. At treeline, last week's storm snow has settled to 20-40cm over the Dec 2 weak layer which consists of the basal facets and surface hoar. A rain crust (1 to 7cm thick) exists within the storm snow up to 2300m on all aspects. The thickness of the rain crust tapers with increasing elevation and is more prevalent in the southern part of the region. Click here for snow profile done on Tuesday in the Dolomite peak area.

Weather Summary

Winds decrease to moderate Wednesday night as flurries move into the region Thursday bringing 5-10 cm. Snow ends Thursday night and winds again pick up to strong on Friday. At treeline, the overnight lows will be around -10C with daytime highs around -5C for the next couple of days.

For more information, click Mountain Weather Forecast.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.