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Archived

Avalanche Forecast

Dec 5th, 2021–Dec 6th, 2021
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.

Recent snowfall is bonding poorly with the underlying crust. Avalanches will move fast on this smooth surface. Be cautious in steep terrain above cliffs and terrain traps, and in wind loaded features. 

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

SUNDAY NIGHT: Partly cloudy with moderate westerly winds at ridgetop with freezing levels at valley bottom.

MONDAY: Cloudy with flurries. Moderate to strong west-northwesterly winds easing into the afternoon. Freezing levels at valley bottom. Alpine highs of -10.

TUESDAY: Partly cloudy. West-northwest winds increase again, with freezing levels at valley bottom. Alpine highs of -8.

WEDNESDAY: Cloudy with light accumulations, freezing levels below 1500m. 

Avalanche Summary

Yesterday, loose dry avalanches were observed out of steep sheltered terrain features. Size 1-1.5 wind slab avalanches were observed in immediate lee features at ridge crest. 

Note there are very few field observations this early in the season. If you head out this weekend, please share your observations and/or photos on the Mountain Information Network!

Snowpack Summary

15-30 cm of new snow sits on top of a thick rain crust on all aspects below 2400m. Westerly winds continue to redistribute the new snow into wind slabs in the alpine and treeline. 

Previously, early season crusts could be found in the snowpack below 2300m, 20-40cm above the ground. At lower elevations these crusts have likely begun to break down from the heavy rainfall, creating a cohesive refrozen snowpack with the thick rain crust at the surface. 

Snowpack depths range from 10-80cm at treeline elevations. Higher elevations may hold a deeper snowpack, but will also be more heavily impacted by recent winds. Rain has washed away the snowpack below 1900m. 

Terrain and Travel

  • Keep in mind the crust offers an excellent bed surface for avalanches.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.

Avalanche Problems

Wind Slabs

Strong westerly winds will continue to build wind slabs in the alpine and treeline. Approach ridge crest and wind loaded features with caution. These wind slabs will be most reactive to human triggering where they overlie a thick, smooth rain crust. 

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2