Avalanche Forecast

Archived

Jan 9th, 2024–Jan 10th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

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.

Lots of wind in the past 24 hours (including reverse wind loading) has formed wind slabs in all alpine and open treeline locations. Cracking and remote triggering windslabs is evident of the changing snowpack.

Confidence

High

Avalanche Summary

A field team went in to the Dogleg area today. Extensive snow transport was happening all day. No new naturals were noted, but a skier remote wind slab to size 1 was triggered from 5 meters away in a gully feature on a SSE aspect ( evidence of reverse loading)

Snowpack Summary

Recent snow accumulations of up to 20cm is being re-distributed by strong and variable winds at ridgetop. Expect wind slabs averaging 30cm thick on virtually all aspects in Alpine terrain, and these do extend down into Treeline elevations in some areas. The reactivity of these wind slabs depends on the previous surface they have formed on. In areas where a buried crust exists, or a layer of weak facets, these new wind slabs will be more touchy. At Treeline and below the early December rain crust remains supportive for the most part. Unfortunately the incoming cold snap may start to change that. Otherwise the basal facets and depth hoar remain unchanged.

Weather Summary

Tuesday evening will bring an additional 5cm. This will total about 20cm of storm snow over the week. Tuesday saw winds in the 60-80km range from the NW at ridge tops.

Wednesday will see day time highs of -15 and cloudy skies. Wednesday evening the Arctic front moves in and current forecasts are showing temps in the -40 range, with out windchill. Yikes!

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Recent wind has varied in direction so watch for wind slabs on all aspects.
Be carefull around freshly wind loaded features.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.