Avalanche Forecast

Issued: Dec 4th, 2017 4:53PM

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

cgarritty, Avalanche Canada

South Rockies.

Lingering wind slab and persistent slab problems are keeping avalanche danger in a holding pattern. Sunshine and warming are set to undermine stability later in the week.

Summary

Confidence

Moderate -

Weather Forecast

Tuesday: A mix of sun and cloud and no new snow. Light northwest winds. Alpine temperatures around -5.Wednesday: Mainly sunny. Light west winds. Freezing level rising to 1300 metres with a strong alpine temperature inversion beginning in the afternoon. Alpine temperatures around -4 and rising with the onset of the inversion. Thursday: Mainly sunny. Light west winds. Freezing level rising to 3500 metres with alpine temperatures around +5. Cooler temperatures at lower elevations due to strong alpine 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 step down and trigger larger avalanches on buried weak layers deeper in the snowpack. Please submit your observations this weekend to the Mountain Information Network.

Snowpack Summary

The snowpack remains highly variable with very little information regarding snowpack structure within the region. Average snowpack depths at upper elevations range from 60-110 cm with scoured snow surfaces on southwesterly slopes and deeper pockets of wind slab on northeasterly slopes. Below the surface exists a series of crusts that were buried near the end of November 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 where snowpack testing North of the region (Kananaskis Country) has yielded hard but sudden results on this layer.

Problems

Wind Slabs

Stiff wind slabs could be reactive to rider triggers at treeline and in the alpine on leeward and cross-loaded slopes.

Use ridges or ribs to avoid pockets of wind loaded snow.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

There are several crusts now buried within the snowpack. Use extra caution in thin snowpack areas where it may be possible to trigger a deeper layer. Triggering a wind slab may also have the potential to step-down to a deeper layer.

Be aware of thin areas that may propogate to deeper instabilites.If triggered wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 5th, 2017 2:00PM