Avalanche Forecast

Issued: Mar 18th, 2020 4:00PM

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

Avalanche Canada cgarritty, Avalanche Canada

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Small new wind slabs are likely to form Wednesday night. Observations will decrease as folks retreat to low-risk activities and social distancing. Be sure to keep risk tolerance to a minimum if you're heading out and to share your observations on the Mountain Information Network.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Cloudy with easing flurries and a trace of new snow. Winds becoming strong and shifting northeast.

Thursday: A mix of sun and cloud with clearing over the day. Moderate northeast winds becoming light and variable, increasing again overnight. Alpine high temperatures around -4.

Friday: A mix of sun and cloud with isolated flurries and a trace of new snow. Easing southwest winds shifting northwest. Alpine high temperatures around -7.

Saturday: Mainly sunny with cloud increasing in the afternoon. Light to moderate southwest winds increasing over the day and overnight. Alpine high temperatures around -7.

Avalanche Summary

No new avalanches were reported over the past couple of days, but reports of wind slab releases from the weekend can be found on the Mountain Information Network.

Loose wet avalanches were also observed throughout the weekend on sunny slopes, especially near rocks and at upper elevations where temperatures were warmest and solar radiation effects were strongest. 

A couple of slabs were also reported as having scrubbed to the ground in shallow snow in the Wheaton area. A large cornice fall on a shaded slope produced no avalanche in a location where the snowpack was deeper.

Looking forward, avalanche problems will likely remain limited to small human triggered wind slabs as well as small wet loose point releases during the heat of the day. The most likely places for these to occur naturally or be human triggered will be on steep, sunward facing terrain where solar radiation might warm things up and loosen bonds in the upper snowpack.

Snowpack Summary

A mix of windblown new snow and wind-scoured surfaces is likely to be found throughout the region. By Thursday, in sheltered areas the new snow is expected to amount to about 5 cm. As a result, small but reactive new wind slabs may overlie sun crust on south and west-facing slopes, but these are likely confined to immediate lee areas.

Recent warming tested the strength of wind slabs as well as the basal snowpack. Neither of these produced notable avalanche activity as a result, however the surface got warm and wet enough to create unstable moist and wet snow on the surface in recent afternoons. There's some evidence that warming temporarily increased instability in shallow snowpack areas as well as in cornices.

Terrain and Travel

  • Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
  • Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches

Problems

Wind Slabs

An icon showing Wind Slabs

Small new wind slabs will likely result from light snowfall and subsequent outflow winds on Wednesday. Increase caution as you encounter new wind-affected snow, considering areas where the greatest wind loading occurred. Wind slab and loose snow releases will be more likely to trigger on steep sun-exposed terrain features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Mar 19th, 2020 5:00PM