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Avalanche Forecast

Dec 5th, 2017–Dec 6th, 2017
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Rockies.

Change is in the air with strong solar effect and the beginning of a warming trend in the forecast. These two factors will begin to undermine stability on Wednesday.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Wednesday: A mix of sun and cloud. Light northwest winds. Alpine temperatures around -3 and rising in the afternoon and evening with the onset of an alpine temperature inversion.Thursday: Mainly sunny with some valley cloud. Freezing level rising from 2700 to 3300 metres over the day with a strong temperature inversion. Alpine temperatures to about +5 with cooler temperatures at lower elevations.Friday: Sunny. Light west winds. Freezing level remaining around 3300 metres with alpine temperatures to about +7. Cooler at lower elevations under the lingering 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 also step down and trigger larger avalanches on buried weak layers deeper in the snowpack. Please submit your observations to the Mountain Information Network.

Snowpack Summary

Average snowpack depths at upper elevations in the region range from 60-110 cm. Snow surfaces have been scoured on southwesterly slopes and deeper pockets of wind slab likely exist on northeasterly slopes. Below the surface, the two crusts that were buried near the end of November can now be found 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. Snowpack testing in the adjacent Kananaskis Country forecast region has yielded hard but sudden results on this layer.

Avalanche Problems

Wind Slabs

Stiff wind slabs could be reactive to rider triggers at treeline and in the alpine on leeward and cross-loaded slopes. Be especially cautious of cross-loaded slopes that see sun exposure on Wednesday.
Watch for whumpfing, hollow sounds, and shooting cracks.Use ridges or ribs to avoid pockets of wind loaded snow.

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.
If triggered, wind slabs may step down to deeper layers and result in large avalanches.Be aware of triggering thin areas that may propagate to deep instabilites more easily.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3