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Avalanche Forecast

Archived

Dec 4th, 2017–Dec 5th, 2017

Alpine
Natural avalanches unlikely, human triggered possible.
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 possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely.

Regions

South Rockies.

Lingering wind slab and persistent slab problems are keeping avalanche danger in a holding pattern. Sunshine and warming are set to undermine stability later in the week.

Confidence

Moderate -

Weather Forecast

Tuesday: A mix of sun and cloud and no new snow. Light northwest winds. Alpine temperatures around -5.Wednesday: Mainly sunny. Light west winds. Freezing level rising to 1300 metres with a strong alpine temperature inversion beginning in the afternoon. Alpine temperatures around -4 and rising with the onset of the inversion. Thursday: Mainly sunny. Light west winds. Freezing level rising to 3500 metres with alpine temperatures around +5. Cooler temperatures at lower elevations due to strong alpine temperature inversion.

Avalanche Summary

No new avalanches have been reported from this region. There is potential for triggering wind slabs on leeward slopes and dry loose avalanches from steeper terrain features. Smaller avalanches may step down and trigger larger avalanches on buried weak layers deeper in the snowpack. Please submit your observations this weekend to the Mountain Information Network.

Snowpack Summary

The snowpack remains highly variable with very little information regarding snowpack structure within the region. Average snowpack depths at upper elevations range from 60-110 cm with scoured snow surfaces on southwesterly slopes and deeper pockets of wind slab on northeasterly slopes. Below the surface exists a series of crusts that were buried near the end of November approximately 40 cm and 70 cm down. Deeper in the snowpack a third crust from the end of October exists as a "facet/crust" combo and has been identified as a potential sliding interface where snowpack testing North of the region (Kananaskis Country) has yielded hard but sudden results on this layer.

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.

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.