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Archived

Avalanche Forecast

Jan 5th, 2023–Jan 6th, 2023
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Careful terrain choices are needed to manage uncertainty about buried weak layers and the ongoing impact of strong wind.

Confidence

Moderate

Avalanche Summary

Preliminary reports from Thursday include a large (size 2) wind slab avalanche that occurred on a southwest slope at treeline during a period of strong wind from the northeast.

Over the weekend and last week, there were several reports of larger (up to size 2.5) natural avalanches at all elevations releasing on a 30 to 60 cm deep facet layer. Triggering an avalanche on this weak layer is still possible under the current conditions.

Snowpack Summary

Strong to extreme wind is forming drifts and wind slabs in alpine terrain and along ridges, while sheltered terrain has 10 to 15 cm of low density snow. This snow may sit above a layer of small surface hoar that will sluff easily in steep terrain. A weak layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. Recent avalanche activity and snowpack tests suggest human-triggering is possible for this layer. We are uncertain about the layer's spatial distribution, but observations suggest it is fairly widespread.

Weather Summary

Thursday night

Mostly cloudy, isolated flurries with up to 3 cm of snow, 40 to 50 km/h wind from the southeast, treeline temperatures around -10 °C.

Friday

Cloudy with afternoon flurries brining up to 5 cm of snow, 40 to 60 km/h wind from the southwest, treeline temperatures warm to -5 °C.

Saturday

Mix of sun and cloud, no precipitation, 30 to 50 km/h wind from the south, treeline temperatures around -5 °C.

Sunday

Mix of sun and cloud, no precipitation, 30 to 50 km/h wind from the southeast, treeline temperatures around -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Use conservative route selection and resist venturing out into complex terrain.
  • Avoid freshly wind loaded terrain features.
  • Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
  • Avoid making assumptions about this layer based on the presence of aggressive tracks on adjacent slopes

Avalanche Problems

Wind Slabs

Strong wind is forecast to shift from northeast to southwest on Friday, which will leave fresh wind slabs on a wide variety of aspects in the alpine and along ridges.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

A layer of facets that formed during the arctic outbreak in December is buried 30 to 60 cm deep. This layer produced natural avalanches last week, and recent snowpack observations suggest it could still be reactive to human triggering on steep rocky slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 2.5