Avalanche Forecast

Issued: Dec 7th, 2017 3:44PM

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.

cgarritty, Avalanche Canada

South Rockies.

Spring weather doesn't mix well with an early season snowpack. Smaller surface instabilities will carry the risk of triggering deep weak layers while warm weather persists.

Summary

Confidence

Moderate -

Weather Forecast

Friday: Sunny with some valley cloud due to lingering alpine temperature inversion. Light west winds. Freezing level to about 3200 metres with alpine temperatures around +5. Cooler at lower elevations.Saturday: Mainly sunny with some valley cloud due to lingering alpine temperature inversion. Light west winds. Freezing level to about 3200 metres with alpine temperatures around +5. Cooler at lower elevations.Sunday: A mix of sun and cloud. LIght to moderate west winds. Freezing level to 3300 metres with alpine temperatures around +6. Cooler at lower elevations.

Avalanche Summary

No new avalanches have been reported from this region. Although Thursday's warm temperatures are likely to have helped bond our 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

Average snowpack depths at upper elevations in the region range from about 50-100 cm. Solar and temperature crusts are expected to have formed on the surface at higher elevations on Thursday. Below the surface, shifting winds over the past few days extended wind slab formation to 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.

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 - Likely

Expected Size

1 - 2

Deep Persistent Slabs

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

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 Friday, especially in steeper terrain. This problem may expand to northerly aspects as warming persists.

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: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 8th, 2017 2:00PM