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Avalanche Forecast

Archived

Mar 10th, 2022–Mar 11th, 2022

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Coast Inland.

Assess for instability before committing to consequential terrain.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

THURSDAY NIGHT: Increasing clouds with no precipitation, 20 to 30 km/h southwest wind, alpine temperature -8 C.

FRIDAY: Cloudy with snowfall, accumulation 1 to 3 cm, 30 to 50 km/h southwest wind, alpine temperature -6 C.

SATURDAY: Cloudy with snowfall, accumulation 2 to 5 cm, 30 km/h south wind, alpine temperature -5 C.

SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 30 km/h southwest wind, alpine temperature -5 C.

Avalanche Summary

A rider triggered a persistent slab avalanche along the Duffey on Wednesday, occurring at 2000 m on a northeast aspect. Another suspected persistent slab avalanche was triggered by a rider on Tuesday in the north of the region. Both slabs were around 30 to 40 cm thick, resulting in small avalanches (size 1 to 1.5). It remains possible that humans could trigger this layer, where it exists.

Looking forward, wind slabs may begin to form on Friday and into the weekend, which may not bond well to underlying layers.

Snowpack Summary

New snow will fall with strong wind, potentially forming small wind slabs in lee terrain features. The snow will accumulate onto variable surfaces. On sun-exposed slopes and on all aspects at low elevations, the snow will build on a hard melt-freeze crust. Elsewhere, it will fall onto previously wind-affected snow at higher elevations and perhaps a thin layer of surface hoar or faceted snow in sheltered areas.

Around 30 to 60 cm deep, sugary faceted grains may be found around a melt-freeze crust that formed February in the north of the region (e.g., Duffey, Hurley). To date, the layer has been most prevalent on north to northeast aspects around 1900 to 2100 m. This layer should be treated as suspect anywhere it exists. Check out this forecaster blog for more info. Various crusts may be found in the south of the region (e.g., Coquihalla, Manning) but reports suggest they are bonding to the snowpack and are not an avalanche concern.

There are no deeper concerns at this time.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.