Avalanche Forecast

Archived

Dec 9th, 2023–Dec 10th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Icefields.

With the current winds plus snow available for transport, watch for dangerous avalanche conditions on specific terrain such as cross-loaded or wind-loaded slopes, Northwest to Northeast aspects, and where local terrain directs windloading patterns. Early season hazards are just below the surface. Read a recent report here.

Confidence

Moderate

Avalanche Summary

No field patrol occurred on Saturday.

On Tuesday to Wednesday, numerous avalanches released due to a 30cm storm. They failed on the buried surface hoar, facet and melt-freeze crust layer. A size 1.5 near Parkers ridge behind Hilda hostel can be found here (Here).

Snowpack Summary

30cm of new snow from last Tuesday formed a persistent slab overlying a weak surface hoar and facet layer or a melt-freeze crust on south and west aspects. The snowpack is 35-45cm in depth with a weak facetted base. A rain crust exists below 1800m. Currently moderate to strong South winds are spawning windslabs on lee aspects.

Weather Summary

The Mountain Weather Forecast is available from Avalanche Canada https://avalanche.ca/weather/forecast

Sunday will be clouds, sun, flurries, -7 °C, and light west winds. Monday and Tuesday will be similar.

Terrain and Travel Advice

Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Keep in mind that human triggering potential persists as natural avalanching tapers off.

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.

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.

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.