Avalanche Forecast

Issued: Jan 1st, 2022 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Avalanche danger will rise towards the end of the day as the next storm blows in. Check out the latest Forecasters' Blog for tips on managing the persistent slab problem in this region.

Summary

Confidence

Moderate - Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

Saturday night: Mostly cloudy. Moderate southwest wind. Alpine temperature around -15 C.

Sunday: Flurries starting in the afternoon, around 5 cm. Moderate to strong southwest wind. Alpine high of -9 C.

Monday: 10-20 cm new snow. Strong southwest wind. High of -7 C.

Tuesday: 10-20 cm new snow. Light to moderate southwest wind. High of -8 C.

Avalanche Summary

On Friday, wind slabs were reactive to explosives up to size 1.5. On Thursday, small (size 1) natural and artificially triggered wind slabs were reported in the alpine.

A few surprisingly deep older crowns were observed between Fernie and Sparwood on Friday. These suspected persistent slab avalanches likely ran on the early December crust around the same time as the explosive triggered size 3 persistent slab reported on December 27th.

Snowpack Summary

Variably wind affected surfaces can be found at upper elevations, including soft to hard wind slabs on a variety of aspects.

The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 80-150 cm. Activity on this layer has been sporadic, most recently reported on December 27th. Since then, snowpack tests have produced no results but we remain wary. This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.

Terrain and Travel

  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

Problems

Wind Slabs

An icon showing Wind Slabs

Fresh wind slabs are likely to form at upper elevations as strong winds precede the next storm. Lingering reactivity may also be observed in older wind slabs on a variety of aspects.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs

A persistent slab problem formed by a crust down 50-150 cm has created a low likelihood, high consequence scenario that is difficult to forecast. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 2nd, 2022 4:00PM

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