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Avalanche Forecast

Archived

Dec 5th, 2017–Dec 6th, 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 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

South Rockies.

Change is in the air with strong solar effect and the beginning of a warming trend in the forecast. These two factors will begin to undermine stability on Wednesday.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Wednesday: A mix of sun and cloud. Light northwest winds. Alpine temperatures around -3 and rising in the afternoon and evening with the onset of an alpine temperature inversion.Thursday: Mainly sunny with some valley cloud. Freezing level rising from 2700 to 3300 metres over the day with a strong temperature inversion. Alpine temperatures to about +5 with cooler temperatures at lower elevations.Friday: Sunny. Light west winds. Freezing level remaining around 3300 metres with alpine temperatures to about +7. Cooler at lower elevations under the lingering 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 also step down and trigger larger avalanches on buried weak layers deeper in the snowpack. Please submit your observations to the Mountain Information Network.

Snowpack Summary

Average snowpack depths at upper elevations in the region range from 60-110 cm. Snow surfaces have been scoured on southwesterly slopes and deeper pockets of wind slab likely exist on northeasterly slopes. Below the surface, the two crusts that were buried near the end of November can now be found 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. Snowpack testing in the adjacent Kananaskis Country forecast region 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.