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Avalanche Forecast

Archived

Feb 20th, 2019–Feb 21st, 2019

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.
Below Treeline
Natural avalanches unlikely.

Regions

Kananaskis.

Look for good skiing in sheltered areas. Recent avalanche activity is a good reminder that MODERATE hazard is not a "green light" to blindly jump into bigger terrain features.

Confidence

Moderate -

Weather Forecast

Thursday will be mainly cloudy with very light flurries. Overnight lows will drop to near -25, with daytime highs near -14. Winds will be light and variable. Similar conditions on Friday.

Avalanche Summary

No new avalanches observed today, but visibility was very limited. Recent strong winds resulted in several loose dry avalanches yesterday up to size 2.0, primarily in very steep Alpine terrain on all aspects. In addition, the deep persistent layer of basal facets finally woke up and a size 2.0 naturally triggered slab occurred on the north end of Tent Bowl around midday on Tuesday. This slide occurred at Treeline and was only about 40m wide, but was between 120 and 140cm deep and failed on the basal facets.

Snowpack Summary

A few cm's of snow fell through the day, but accumulations were minimal. New wind slabs can be found in Alpine and Treeline features on all aspects, but we are unsure of the extent of these due to a lack of field observations today. The mid pack has enough strength and depth (in most places) that triggering the bottom layers is unlikely. The key to avoiding trouble is avoiding thin areas where the bridging is minimal.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.