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Avalanche Forecast

Dec 24th, 2022–Dec 25th, 2022
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Natural avalanche activity will taper off Sunday, but human triggering will remain likely for the next while.

Increased winds, warmer temps, and new snow have added load to a very weak faceted snowpack. A conservative approach to terrain is recommended through the holidays until things improve.

Confidence

Moderate

Avalanche Summary

Newly formed wind slabs have been reactive to skier and explosive control in the past couple of days. Local ski hills and touring groups reported several new avalanches up to size 1.5 with failures occasionally stepping down into the basal facets to create larger slides. Wind-triggered sluffing in extreme terrain has also been observed.

Snowpack Summary

5-15 cm of new snow and wind are creating new slabs of varying thickness overtop of a weak faceted snowpack. The Dec 17 layer of facets and surface hoar is down 10-25 cm, and the Nov 16 facet, crust and surface hoar layer is down 30-60 cm, just above the weak basal facets. Both of these layers have been reactive in the past couple of days and avalanches triggered on either of these layers can quickly step down to the basal facets producing larger avalanches.

Total snowpack depths at treeline range from 60-120 cms.

Weather Summary

Another 5-10 cm of snow with extreme west winds is expected Saturday night into Sunday. On Sunday an upper ridge develops over the Rockies and the alpine winds will decrease slightly, becoming moderate-strong out of the west. Some flurries are expected Sunday along the divide with a mix of sun and cloud to the east. Alpine temperatures will stay between -5 to -10°C during the day, dropping to -10 to -15°C Sunday night.

Terrain and Travel Advice

  • Watch for fresh storm slabs building throughout the day.
  • Uncertainty is best managed through conservative terrain choices at this time.

Avalanche Problems

Wind Slabs

Strong S-W winds and 5-15 cm of new snow continue to build fresh wind slabs in alpine and treeline terrain. These new wind slabs overly a very weak faceted snowpack. If triggered the slab will likely gouge down to the deep persistent problem and increase in size.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The whole snowpack is thin, weak and facetted, but the biggest facets and depth hoar are at the bottom. New snow, wind, and warm temperatures are increasing the slab over top of this weak base, and we are expecting more avalanche activity on the basal facets over the next week. As this surface slab develops we may also start seeing more avalanche activity below treeline on this problem.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2.5