Avalanche Forecast

Archived

Dec 10th, 2023–Dec 11th, 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 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.

Regions

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

With strong winds on Saturday plus recent snow available for transport, be alert for dangerous avalanche conditions on specific terrain such as cross-loaded or wind-loaded slopes, Northwest to East aspects, and where local terrain directs windloading patterns. Early season hazards are just below the surface.

Confidence

Moderate

Avalanche Summary

Sunday's Icefield patrol had limited visibility and the alpine was obscured. Three size 1-2 wind-slabs were observed in the Parker area where one would suspect the buried surface hoar was sheltered, present, and preserved. These appeared to have occurred on Thursday or Friday.

Snowpack Summary

30cm of new snow from last Tuesday formed a persistent slab overlying a surface hoar or facet layer or a melt-freeze crust on south and west aspects. The snowpack is 40-60cm deep with a weak facetted base. A rain crust exists below 1800m. Saturday's moderate to strong South winds spawned windslabs on lee aspects.

Weather Summary

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

Monday to Wednesday will be sun, clouds, -8 °C, and light winds.

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

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.

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.