Avalanche Forecast

Issued: Jan 5th, 2023 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada shorton, Avalanche Canada

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

Summary

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

Problems

Wind Slabs

An icon showing 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

An icon showing 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

Valid until: Jan 6th, 2023 4:00PM