Avalanche Forecast

Archived

Dec 28th, 2022–Dec 29th, 2022

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

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

Warm temps continue to settle the upper snowpack into a slab at tree line and above and have become sensitive to triggering in the alpine. Backcountry users need to adopt a conservative mindset and make cautious terrain decisions for the foreseeable future.

Confidence

Moderate

Avalanche Summary

One Min report from Tuesday at Burstall Pass talks about remote triggering a size 1 from 30m away.

Snowpack Summary

Up to 5cm of recent snow overlies the December 26 rain crust that can be found to at least 2200m. The upper snowpack has gained some density with the warm temps. Wind slabs are present in Alpine and exposed treeline terrain, particularly just below ridgelines and in gully features. Some of these wind slabs have been reactive to remote triggering in the alpine. Below this new snow and wind slabs, the snowpack is very weak. Forecasters are tracking the Dec 16th surface hoar/facet layer down 10 to 20cm and the mid-November facet/surface hoar/depth hoar layer down 50 to 80cm. If avalanches are initiated on these layers they will likely step to ground through the very weak basal facets/depth hoar. It's not a pretty picture!

Weather Summary

Thursday will bring a mix of sun and cloud with moderate SW winds. Temperatures in the alpine will be between -6c and -11c.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Be especially cautious as you transition into wind affected terrain.

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.