Avalanche Forecast

Issued: Jan 1st, 2023 4:00PM

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

Avalanche Canada mconlan, Avalanche Canada

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Triggering large persistent slab avalanches remains possible.

Summary

Confidence

Moderate

Avalanche Summary

A few small to large (size 1 to 2) storm slab avalanches were triggered naturally and by explosives on Friday and Saturday, generally 30 to 60 cm deep within recent storm snow.

Large (size 2 to 3) avalanches occurred within the past week, with some of them stepping down to deeper weak layers. We suspect it is becoming more difficult to trigger these deeper layers, however caution should be taken in challenging or complex terrain given the uncertainty and consequence of large avalanches.

Snowpack Summary

Around 50 cm of snow sits on a hard melt-freeze crust found up to treeline elevations formed by rain on December 26. Moist snow or a surface crust may be found up to around 1600 m on all aspects and up to ridgetop on sun-exposed slopes.

Two deeper layers of surface hoar and facets could still be triggered in specific terrain. These include a 40 to 80 cm deep layer buried mid-December and an 80 to 150 cm deep layer buried mid-November. These layers are generally deeper around Fernie and shallower towards Sparwood and Elkford. The layers may be easier to trigger where they are buried within the top 100 cm of the snowpack.

Weather Summary

Sunday Night

Mostly cloudy with trace snowfall, 10 km/h west wind, treeline temperature -6 °C.

Monday

Mix of sun and cloud with no precipitation, 10 km/h south wind, treeline temperature -5 °C.

Tuesday

Mostly sunny with no precipitation, 10 to 20 km/h southwest wind, treeline temperature -8 °C.

Wednesday

Cloudy with isolated flurries, 20 to 40 km/h southwest wind, treeline temperature -10 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Buried weak layers are likely gaining strength but the possibility of triggering a large persistent slab avalanche remains. There are two weak layers, both composed of surface hoar and facets, anywhere from 40 to 150 cm deep. It may be more likely to trigger these layers where they are buried relatively shallow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Jan 2nd, 2023 4:00PM