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Avalanche Forecast

Archived

Jan 21st, 2024–Jan 22nd, 2024

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

Regions

Blue River, Premier, Clemina, Esplanade, North Monashee, North Selkirk.

Wind slabs may persist longer than normal where they rest on a weak layer of facets.

Persistent weakness in the snowpack warrants a conservative approach to large or steep slopes.

Confidence

Moderate

Avalanche Summary

A few natural loose dry avalanches were reported over the weekend (size 1 to 2) out of steep alpine terrain.

Natural wind slab activity has started to taper off, however, small (size 1 to 2) rider triggered wind slabs were still being reported on Friday.

Earlier in the storm on Wednesday, two persistent slab avalanches (size 1 and 2) were remotely triggered by skiers in the Northern Selkirks. These avalanches occurred on north aspects at treeline.

Snowpack Summary

20 to 30 cm of surface snow is now resting on a variety of old snow surfaces including faceted snow, surface hoar and firm wind slabs in open terrain at treeline and above.

Down 60 to 80 cm a crust, facet, and/or surface hoar layer exists.

130+ cm down another surface hoar layer exists that was buried in early December. This seems to be of most concern above 2000 m where a robust crust doesn't exist above it, or in shallow snowpack areas.

Weather Summary

Sunday Night

Cloudy with up to 3 cm of snow, south alpine wind 10-40 km/h, treeline temperature around -6 °C.

Monday

Cloudy with up to 3 cm of snow, south alpine wind 10-40 km/h, treeline temperature around -2 °C.

Tuesday

Cloudy with 5-15 cm of snow, south alpine wind 10-30 km/h, treeline temperature around -2 °C.

Wednesday

Cloudy with up to 5 cm of snow, southwest alpine wind 20-40 km/h, treeline temperature around -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.

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.

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.