Avalanche Forecast

Issued: Dec 10th, 2017 3:42PM

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.

Warm temperatures and solar radiation may elevate the avalanche danger at higher elevations on Monday.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Expect mainly clear skies and valley cloud for the forecast period. An inversion is forecast for all 3 days with high alpine temperatures peaking at 5 degrees on Monday and Tuesday. Winds are expected to remain light to moderate from the west.

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. The band of warm air associated with the inversion has been hovering at elevations higher than most peaks in the area. If this band of warm air drops, we may see a round of loose wet avalanche activity in steep, sun-exposed terrain.Please submit your observations to the Mountain Information Network.

Snowpack Summary

Stiff wind slabs exist on a wide range of aspects in alpine and exposed treeline terrain. On sheltered treeline and below treeline slopes, I suspect light amounts of low-density snow intermingle with surface hoar and surface facets.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

Variable winds from last week have formed wind slabs on a wide range of aspects at higher elevations. Be especially cautious of reverse loaded or cross-loaded slopes that see sun exposure.

If triggered, wind slabs may step down to deeper layers and result in large avalanches.Use ridges or ribs to avoid pockets of wind loaded snow.Be alert to conditions that change with elevation.

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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Loose Wet

The band of warm air associated with the inversion has been hovering at elevations higher than most peaks in the area. If this band of warm air drops, we may see a round of loose wet avalanche activity in steep, sun-exposed terrain.

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

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 11th, 2017 2:00PM