Avalanche Forecast

Issued: Dec 25th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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South Coast.

Heavy snowfall and wind are building reactive storm slabs. Stick to low angle, wind sheltered terrain away from overhead hazard.

Summary

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

Friday night: 15-20 cm new snow, moderate southwest wind, freezing level 1000 m.

Saturday: 20-30 cm new snow, moderate south wind, treeline temperature -3 C, freezing level 1000 m.

Sunday: Clearing, light southwest wind, treeline temperature -4 C, freezing level 800 m.

Monday: Sunny, light northwest wind, treeline temperature -3 C, freezing level 800 m.

Avalanche Summary

Two skier-triggered avalanches were observed on Tuesday within the recent storm snow, as seen in the MINs here and here. With new snow coming on the weekend, skier triggering of storm slab avalanches remains likely.

Snowpack Summary

30-50 cm of new snow is forecast to fall by the end of the day Saturday. The storm came in warm, so the new snow may adhere well to previous surfaces. These include a temperature crust at low elevations and solar aspects, and wind slabs at upper elevations on variety of aspects due to recent variable wind directions. 

Around 50-70 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

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Minimize exposure during periods of heavy loading from new snow and wind.
  • Keep in mind the crust offers an excellent bed surface for avalanches.
  • Don't let the desire for deep powder pull you into high consequence terrain.

Problems

Storm Slabs

An icon showing Storm Slabs

30-40 cm of new snow is forecast to fall by the end of the day Saturday. This snow came in warm and is expected to adhere well to older snow. Thicker wind loaded pockets may be found in lee terrain features.

Around 50-60 cm of snow now overlies a thick crust. If triggered, storm slabs can slide easily on the crust. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Almost Certain

Expected Size

1 - 2

Valid until: Dec 26th, 2020 4:00PM

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