Avalanche Forecast

Issued: Mar 29th, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Storm slabs may remain reactive to human triggers as natural avalanche activity tapers off. Start with small terrain features, look for sign of instability and gather information before considering bigger terrain.

Summary

Confidence

Moderate -

Weather Forecast

Monday night: Scattered flurries. Light to moderate northwest wind. Freezing level valley bottom. Alpine temperature -13.

Tuesday: Scattered flurries. Light to moderate northwest wind. Freezing level 1400 m. Alpine temperature -9.

Wednesday: Sunny. Light southwest wind. Freezing level 2000 m. Alpine temperature -1.

Thursday: Sunny. Moderate southwest wind. Freezing level 2000 m. Alpine temperature -1.

Avalanche Summary

Preliminary reports of avalanche activity during the storm include one visually observed and numerous audible natural storm slabs suspected to be in the size 3-3.5 range in the southeast corner of the region.

Notable reports of avalanche activity prior to the storm include:

  • A size 3 slab avalanche was observed northeast of Revelstoke on Wednesday. The avalanche failed on the ground on a south aspect at 1600 m. 
  • In neighboring Glacier National Park and South Columbia regions, several natural cornice falls triggered deep slab avalanches size 2-3.

Snowpack Summary

The weekend's storm dropped 20-50 cm over the Selkirk mountains in the south of the region and 5-10 cm elsewhere. This snow came with wind from southwest to northwest, loading thick slabs in lee features at upper elevations. Reports from Monday have indicated that the new snow is bonding well with underlying surfaces. Crusty and/or moist surfaces exist below treeline depending on elevation and time of day.

At alpine and treeline elevations, a widespread crust exists (except on north-facing slopes above 1800 m) buried 50-100 cm deep. Overall the snow seems to be bonding well at this interface, although there have been a few isolated avalanches running on crust layers over the past few week.

Terrain and Travel

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Start with conservative lines and watch for clues of instability.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Storm Slabs

An icon showing Storm Slabs

Storm slabs may remain reactive to human triggers in wind loaded terrain features. Wind direction has varied from southwest to northwest so watch for these deep pockets on a variety of aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are likely fragile due to rapid growth with recent snow and wind.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 30th, 2021 4:00PM