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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

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

This is not your typical coastal mountain snowpack - it is generally facetted, weak and shallow, with a significant weakness at the bottom of the snowpack. Assess for stiff, cohesive, wind slabs on the surface, that if triggered have the potential to step down to deeper weak layers.

Confidence

Moderate

Avalanche Summary

No new avalanche activity has been reported over 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

Recent storm snow continues to facet with current cold temperatures. These sugary crystals will be easily redistributed by the current cold, Northerly winds into drifts and stiff wind slabs.

In general, the snowpack is weak, facetted, and shallow for mid-December. Snowpack depths generally range from 80-120cm at treeline. Widespread large basal facets and even depth hoar have been reported. At the moment much of the snowpack lacks much cohesion for this weak basal snow to be an issue. However, as the upper snowpack gains cohesion, with time and more snow, this deep persistent layer will likely become more of a concern.

Weather Summary

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

Sunday night

Clear. No precipitation. Temperatures around -25 to -30 C and generally light Northeast winds in the alpine.

Monday

A mix of sun and cloud, with no precipitation. Temperatures -20 to -25 C and light Northeast winds in the alpine.

Tuesday

A mix of sun and cloud, with no precipitation. Temperatures -20 to -25 C and light North winds in the alpine.

Wednesday

A mix of sun and cloud, with no precipitation. Temperatures -20 to -25 C and light Northeast winds.

Tuesday

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.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.