Avalanche Forecast

Archived

Dec 10th, 2022–Dec 11th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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.

Regions

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

The snowpack is very sensitive to human-triggering. Forecasters were able to easily remote and skier trigger avalanches failing down 40-50cm at treeline on Friday. Avoid steep, convex and unsupported slopes as the snowpack adjust to this new load.

Confidence

High

Avalanche Summary

On Friday numerous skier controlled size 1 avalanches were triggered by forecasters. These failures occurred down 40cm on the Nov 25 facet layer.

Snowpack Summary

A few cm's of new snow in the past 24hrs. The winds have been strong in the Alpine with many windward slopes stripped bare to rock, with pockets of hard wind slab on the lee side. There are two main layers of concern found in the snowpack. The Nov 25 facet layer is down 15 to 30cm and the Nov 16 surface hoar is buried 30 to 50cm. Both of these layers are producing whoomphs, cracking and very easy test score in snowpack tests. In addition, the basal layers are fully facetted. Forecasters have very little confidence in the snowpack.

Weather Summary

Sunday should be a mix of sun and cloud with temperatures climbing to -8C by midday. A couple of cm's of snow are expected, with generally light SW winds.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be especially cautious as you transition into wind affected terrain.
Avoid convexities, steep unsupported terrain and rocky outcroppings.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Remote triggering is a concern, watch out for adjacent and overhead slopes.
Watch for areas of hard wind slab on alpine features.

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.

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.