Avalanche Forecast

Issued: Apr 21st, 2021 4:00PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet and Cornices.

Avalanche Canada swerner, Avalanche Canada

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 Plan your day around avoiding sun-exposed slopes and cornices at peak daytime warming. Wet loose avalanches are possible, especially from southerly slopes and terrain features. 

Summary

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack. Uncertainty is due to the limited number of field observations.

Weather Forecast

Overnight Wednesday: Mostly clear with some upper-level cloud entering the region. Light northwest wind and freezing levels dropping to 600 m. 

Thursday: Mix of sun and cloud. Ridgetop wind light from the northeast. Alpine temperatures near -2 and freezing levels 1700 m. 

Friday: A mix of sun and cloud. Light winds from the East. Alpine temperatures near -2 and freezing levels 1600 m.

Saturday: Snow up to 6 cm. Alpine temperatures near -4 and freezing levels 1600 m. 

Avalanche Summary

On Tuesday, natural wet loose avalanches up to size 1.5 were spotted from steep solar terrain and explosive control work initiated a size 3.5 wet slab from a large South facing avalanche path.

On Monday, wets slabs and glide slabs up to size 3 were reported. Natural wet loose avalanche activity up to size 2 continues with these warm days.

Last weekend, widespread loose wet and cornice activity was still ongoing. The Coquihalla zone also saw glide slabs and wet slabs up to size 3.

Snowpack Summary

A melt-freeze crust exists to the mountain top on solar slopes and up to 2200 m on polar slopes. Above 2200 m on North facing terrain, you may find dry snow and a generally well-settled snowpack. Below treeline elevations, the snowpack has been isothermal but will likely lock up as freezing levels drop. 

Cornices are large and looming along ridgelines. They are weak and very unpredictable. 

Terrain and Travel

  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Keep in mind that wet avalanches can be destructive due to their high density.

Problems

Loose Wet

An icon showing Loose Wet

Wet loose avalanche activity is possible on sun-exposed slopes. These avalanches are generally smaller than wet slabs but they can gather mass as they travel and reach low elevations.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are at their largest at this time of year, and become weaker with warm temperatures and solar radiation.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 22nd, 2021 4:00PM

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