Avalanche Forecast

Issued: Dec 24th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Storm slabs will be most reactive where the wind has loaded deep pockets of snow over a crust. The crust makes a slick bed surface for avalanches.

Summary

Confidence

Moderate -

Weather Forecast

Thursday night: Increasing cloud, wind increasing to strong southwest, freezing level dropping 2000 to 1200 m.

Friday: 10-15 cm new snow, wind easing to moderate southwest, treeline temperature 0 C, freezing level rising 1000 to 1400 m.

Saturday: 15-20 cm new snow overnight, moderate south wind, treeline temperature -1 C, freezing level 1200 m.

Sunday: Clearing, moderate west wind, freezing level dropping 2000 to 1000 m.

Avalanche Summary

Two skier-triggered avalanches were observed on Tuesday within the recent storm snow, as seen in the MINs here and here. The likelihood of triggering similar avalanches will remain possible until we see evidence that the snow is bonding to the underlying crust.

Snowpack Summary

10-15 cm of warm, dense snow is forecast to fall over the day Friday. The new snow falls ontop of a temperature crust on solar aspects at upper elevations, which formed during the warm, sunny period on Thursday. On shady aspects that have remained dry, new snow falls over wind slabs on variety of aspects due to recent variable wind directions. 

Around 30 cm of snow now overlies a hard melt-freeze crust up to around 1500 m.

The remainder of the snowpack is well-settled and hosts numerous other melt-freeze crusts which are well bonded to the surrounding snow.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Closely monitor how the new snow is bonding to the crust.
  • Keep in mind the crust offers an excellent bed surface for avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs

With 10-15 cm falling over the day Friday, around 30 cm of snow now overlies a hard crust. If triggered, storm slabs will slide easily on the crust. Thicker wind slabs may also be found at the mountain tops on all aspects due to variable wind directions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 25th, 2020 4:00PM