Avalanche Forecast

Archived

Jan 4th, 2023–Jan 5th, 2023

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.

An inversion over the past few days has kept the cool air in the lower elevations and warm air in alpine terrain. The snowpack is not really changing at this time. Persistent slabs overlying a weak facetted "house of cards" snowpack. Avoid big features and be patient for Ullr to maybe give us some snow.

Confidence

High

Avalanche Summary

Isolated recent natural avalanche activity up to size 2.5 from Alpine features. These slides initiated as a persistent slab and then stepped to ground. A few loose dry were also observed from steep unskiable terrain.

Snowpack Summary

Large surface hoar was found today up to 2200m. This may be a layer to watch in the future.

Otherwise not much is changing in the snowpack (and that's not a good thing!). The mid-December surface hoar layer down 30cm at Treeline is reacting as a persistent slab with compression tests in the moderate range. Below this, the remainder of the snowpack is heavily facetted. Any avalanche triggered in the upper snowpack will almost certainly step down to the ground.

Forecasters are approaching all terrain conservatively and do not have much confidence in the snow pack, as it's one of the worst we've seen in many, many years.

Weather Summary

High pressure continues, bringing mainly clear skies and no precipitation. An inversion with warmer temperatures at higher elevations has been persistent over the past few days and we expect it to continue into the next few days.

Burn a pair of you favorite old ski socks to try to encourage the Ullr to create some snow for us.

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.