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Archived

Avalanche Forecast

Dec 2nd, 2021–Dec 3rd, 2021
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
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: Little Yoho.

Cooler temperatures are on the way which should improve conditions slowly over the next few days. However, users can still trigger large, destructive avalanches. Mount Dennis avalanche closure zone in Yoho closed on Friday.

Weather Forecast

Thursday AM, alpine temperatures will decrease to -15C and valley bottom temperatures at -7 to -10C. Temperatures should stay below freezing, with moderate alpine winds diminishing over the day. No snow expected Thursday.

Snowpack Summary

Wednesday's storm started as rain to 2400m for most of the day, saturating the snowpack, and turned to snow early Thursday AM. Anywhere from 30-80+cm was deposited from this storm in the alpine with high settlement from warm temperatures. A midpack Nov.15 crust is found below 2100m, and the Nov. 5 crust/facet layer exists near the ground.

Avalanche Summary

Wednesday saw many natural avalanches to size 3.5, and Thursday produced sporadic results. Some targets produced minimal results, but some results were 40-100cm deep storm slabs, some stepping down to the basal crust/facets and entraining loose wet snow below treeline. A few crowns where it stepped down were 200cm deep.

Confidence

The weather pattern is stable on Friday

Avalanche Problems

Storm Slabs

There has been an estimated 40 to 80+cm of new snow with strong winds from Wednesday's storm. Treeline slabs are softer due to lack of wind and have been more reactive to explosives, with more wind effect seen in the alpine.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3

Deep Persistent Slabs

Explosives produced slabs on the basal Nov 5 crust/facets. Some initiated on this layer, while others were "step down" avalanches. Cooling temperatures should decrease the likelihood over time, but there is uncertainty as to how long this will take.

  • Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3.5