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Avalanche Forecast

Archived

Dec 22nd, 2023–Dec 23rd, 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.

Residual windslabs remain on lee alpine features. Despite the improvement in travel, the unpredictable nature of the very weak snow at the bottom of the snowpack inspires little confidence. Keep to terrain choices where large steep features can be avoided.

Days are short: aim to be back to the trailhead by about 4 PM

Confidence

Moderate

Avalanche Summary

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 only a few, 10-20cm deep, wind slabs that were observed local to their explosive shots Thursday & Friday in alpine features.

Snowpack Summary

Recent SW winds created some wind slabs in alpine. There may be a new surface crust up to 2000 m from the past few unseasonably warm days.

The mid-pack is generally carrying skis right now (not boots) with ski penetrations of 5-10 cm. In southern parts of the region, there is a mid-pack rain crust that is up to 7 cm thick and has been observed as high as 2300m. It is not as high in northern areas.

The lower snowpack is facetted and very weak.

Treeline snowpack depths range from 50-95cm.

Weather Summary

Temperatures drop tonight with alpine lows reaching -18C as a cold front descends. Expect to see a few flurries Friday night followed by a clearing trend on Saturday with light westerly winds.

Temperatures will continue to drop through Saturday, with lows -20C and highs around -12C for Sunday and Christmas day.

For more information, click Mountain Weather Forecast.

Terrain and Travel Advice

  • 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.