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Avalanche Forecast

Archived

Dec 23rd, 2023–Dec 24th, 2023

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.
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.

Watch for wind loading in the alpine. Travel has improved over the past week, but the unpredictable nature of the weak snow at the bottom of the snowpack inspires little confidence. Continue to treat large steep features with caution!

The days are short and temps are dropping. Bring gear to deal with any unexpected delays.

Confidence

No Rating

Avalanche Summary

A few new size 1-1.5 natural wind slabs and loose dry avalanches in steep lee alpine terrain were observed on Saturday.

Whumpfing is still being reported from alpine areas (Dolomite Circuit, Hector shoulder). We suspect this is occurring on the weak basal layer.

Ski hill snow safety teams reported a few size 1-1.5 wind slabs as a result of explosives and ski-cutting work in alpine features.

Snowpack Summary

5-10 cm of new snow at tree line with moderate SW winds are creating new wind slabs in alpine and exposed treeline terrain. Low elevations have a crust of refrozen snow. 15-50 cm of snow sits over the Dec 5 rain crust that exists as high as 2300 m, and is more prevalent in the southern part of the forecast area. The base of the snowpack is a mix of weak basal facets and a spotty crust from late Oct. Treeline snow depths range from 50-95 cm. Many early-season hazards still exist.

Weather Summary

An upper ridge will bring mainly clear skies to the Alberta Rockies. West to southwest winds at ridgetop will increase through the day bringing moderate to strong winds by the afternoon. Temperatures drop tonight with alpine lows reaching -20°C overnight and highs between -10 and -5°C with a possible inversion in the alpine.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • Be especially cautious as you transition into wind affected terrain.
  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
  • Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.