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Avalanche Forecast

Archived

Dec 18th, 2022–Dec 19th, 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.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus, Sasquatch, Tetrahedron.

This is not your typical coastal mountain snowpack! A number of buried weak layers persist and will likely become more of a concern as the upper snowpack settles and gains cohesion. Deeper weak layers could potentially be triggered by small wind slabs on the surface.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported in the last few days.

If you head out into the mountains, please share your photos or observations on the Mountain Information Network. Your information helps us understand local conditions!

Snowpack Summary

Cold temperatures continue to facet the surface snow. These sugary crystals will be easily redistributed by the current cold, northerly winds into drifts and stiff wind slabs.

Concerns in the mid and lower snowpack are dominated by two weak layers:

  • A weak surface hoar layer buried in early buried December is 30-60 cm deep and looks to be a bigger problem in sheltered terrain at lower elevations. Professionals are closely tracking this layer as the overlaying snow settles and gains cohesion.

  • A widespread crust and facet layer from late November is buried 40-80 cm deep, found on all aspects and elevations.

Total snow depths remain low for December with about 90 to 140 cm at treeline and up to 200 cm in the alpine.

Weather Summary

Cold arctic air dominates the weather throughout BC this week. High uncertainty remains over the potential for snowfall starting Tuesday.

Sunday night

Clear. No precipitation. Temperatures around -25 C and generally light Northeast winds in the alpine.

Monday

Mostly clear with no precipitation. Temperatures -20 to -25 C and light Northeast winds in the alpine.

Tuesday

Mostly cloudy with potential for flurries. Temperatures around -20 C and light North winds in the alpine.

Wednesday

A mix of sun and cloud, with no precipitation. Temperatures -15 to -20 C and light Northeast winds.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.