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Avalanche Forecast

Archived

Jan 21st, 2020–Jan 22nd, 2020

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, human triggered possible.

Regions

Kananaskis.

Warm temps and strong winds have been a shock to the snowpack of late. Any change that happens quickly is rarely good. Lots of drummy windslabs out there at treeline and above. If they fail, good chance the basal layers will wake up.  

Confidence

No Rating -

Weather Forecast

Light snow is forecast to begin overnight as temperatures begin to cool slightly. Winds are forecast to continue in the moderate range out of the SW. Freezing levels are forecast to be around 1200m with a mainly cloudy sky.  

Avalanche Summary

No new avalanches were observed today.  

Snowpack Summary

The snowpack is settling with the recent warm weather. Thin melt freeze crusts were observed on solar aspects this morning. Wind slabs are now widespread at all elevations and on all aspects except westerly. These slabs are of varying thickness and also have highly inconsistent results in snowpack stability tests. Forecasters continue to monitor the Dec 31 layer (surface hoar or facets) that is now buried 50cm on average. The layer has not been particularly active in avalanche activity, but it's a good thing to keep an eye on. The mid-pack is unusually strong and settled for this part of the mountain range. While, in many ways this is a good thing, it also serves to mask the significant basal weakness. There is still potential to trigger the basal layers, particularly in shallow snowpack areas, which could result in very large, destructive avalanches.

Terrain and Travel

  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Cornices become weak with daytime heating.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

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.