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Avalanche Forecast

Archived

Dec 9th, 2017–Dec 10th, 2017

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, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Rockies.

Weaknesses deep in the snowpack will heal much more slowly than wind slabs. As alpine temperatures rise, keep your guard up around big overhead terrain and in thin snowpack areas.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Expect mainly clear skies and a temperature inversion for the forecast period. Alpine temperatures are expected to reach 2 degrees on Sunday and then climb to 5 degrees on Monday and Tuesday. Ridgetop winds are forecast to be moderate from the southwest on Sunday, becoming light on Monday and Tuesday.

Avalanche Summary

No new avalanches have been reported from this region. Although warm daytime temperatures and overnight cooling are likely helping bond recent wind slabs to the surface, the potential for releases deeper in the snowpack will remain elevated as these warm temperatures persist. Thin and variable snowpack depth areas will be the most likely trigger points for a deep release.Please submit your observations to the Mountain Information Network.

Snowpack Summary

Solar and temperature crusts are expected to have formed on some surfaces over the past few days. In shaded higher elevation terrain where surface snow remained cold and unconsolidated, recent shifting winds redistributed loose snow forming stiff wind slabs on a wide range of aspects at treeline and above. The two crusts that were buried near the end of November can now be found approximately 30 cm and 60 cm down. A third crust from the end of October exists as a "facet/crust" combo near the base of the snowpack. Snowpack testing in the adjacent Kananaskis Country forecast region has yielded hard but sudden results on this layer.Average snowpack depths at upper elevations in the region range from about 50-100 cm.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.