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Avalanche Forecast

Jan 7th, 2017–Jan 8th, 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
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
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

Regions: South Rockies.

A bit of new snow combined with sustained winds will keep our wind slab problem alive and well. Even if the rating is still Moderate, stability will be decreasing with any new snowfall.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

Sunday: Cloudy with sunny periods and isolated flurries bringing a trace of new snow. Winds light from the southeast. Temperature inversion bringing alpine temperatures to -8.Monday: Mainly cloudy with isolated flurries bringing a trace of new snow. Winds light gusting to extreme from the southwest. Alpine temperatures to -7.Tuesday: A mix of sun and cloud with no new snow. Winds light to moderate from the northeast. Alpine temperatures to -13.

Avalanche Summary

Explosives control in the southern Alberta Rockies produced a Size 2 result in a heavily wind loaded start zone on Friday. A pocket of wind slab released to Size 1 under skier traffic in the same area on Friday. Wind slabs are expected to remain reactive to human triggers with ongoing winds keeping slabs touchy and highly variable snowpack depths keeping trigger points easy to strike.

Snowpack Summary

Recent moderate northerly winds have continued to load our wind slabs on south and west aspects. In some areas these wind slabs may be sitting on an old scoured surface that was stripped by previous strong westerly winds that developed wind slabs on north and east aspects. The newer wind slabs are probably easier to trigger, but the old wind slabs may continue to release with the added load of a rider, especially where they are sitting on a shallow weak sugary base. The mid snowpack is generally right side up, with the mid-December interface down 40-80cms, giving inconsistent results in snowpack tests. There is some faceting below this interface but resistances are good and showing signs of rounding (stabilizing). Travel conditions have been challenging (especially at lower elevations) and little change is expected until a significant warm up helps to settle the snowpack.

Avalanche Problems

Wind Slabs

Recent strong winds have created wind slabs on a wide range of aspects. Analyze each slope for patterns of wind loading and be especially cautious of thin trigger points. A small wind slab avalanche can trigger deeper weaknesses in the snowpack.
Be cautious as you transition into wind affected terrain.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be alert to conditions that change with aspect and elevation.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

Where denser snow overlies weak, sugary snow, there is the potential to trigger large, dangerous avalanches. Dig down and test weak layers before committing to any steep slope and avoid overhead hazard.
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Danger exists where denser snow overlies weak, sugary snow below.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3