Avalanche Forecast

Issued: Dec 9th, 2017 3:25PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Deep Persistent Slabs and Loose Wet.

jlammers, Avalanche Canada

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.

Summary

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

A recent wind shift from southwest to north means that wind slabs now exist on a wide range of aspects at higher elevations. Be especially cautious of reverse loaded or cross-loaded slopes that see sun exposure.

Use ridges or ribs to avoid pockets of wind loaded snow.If triggered, wind slabs may step down to deeper layers and result in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

Several persistent weak layers exist at the base of the snowpack. The likelihood of triggering one of these weaknesses will be elevated while warm weather persists at higher elevations.

Be aware of triggering thin areas that may propagate to deep instabilites more easily.Minimize your exposure to overhead avalanche terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Loose Wet

Warm, sun-exposed slopes could continue to produce wet loose avalanches either naturally or with rider triggers on Sunday, especially in steeper terrain.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 10th, 2017 2:00PM