Avalanche Forecast

Archived

Jan 15th, 2023–Jan 16th, 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

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

The lower half of the snowpack is still weak, and human triggering of large, destructive avalanches is still possible. Despite the MODERATE hazard rating, conservative terrain selection is still critical.

Confidence

High

Avalanche Summary

One size 2 slab was observed Saturday on the SE aspect of Hero's Knob at 2100m, possibly triggered by the warm temps. Nothing new was observed on Sunday.

Snowpack Summary

A couple of cm's of fresh snow overlies a very thin crust, but thankfully this crust disappears above 1900 to 2000m depending on the valley. A buried layer of surface hoar down 15 to 30cm at treeline continues to produce shears, but the main concern in the snowpack is the persistent moderate shears failing down 70 to 80cm in the mid-November facets. The lower half of the snowpack remains very weak, and any avalanche initiated in the upper snowpack will likely step down to the lower weaknesses. Thin and rocky areas are of particular concern for triggering the deeper weak layers. Below 2100m the snowpack does not support the weight of a skier if you leave an established skin track.

Weather Summary

Monday will be mainly cloudy with very light flurries in the morning. Snow accumulations should be near 2cm. Temps will climb to -5C by midday. Winds will be moderate from the SW, decreasing to light by late morning.

Tuesday will be cloudy and a little cooler.

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.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.