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Avalanche Forecast

Archived

Jan 3rd, 2022–Jan 4th, 2022

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

Regions

Sea To Sky.

Storm and wind slabs will likely remain touchy to human traffic. The snow is loading a buried weak layer, which could produce very large and destructive avalanches.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

MONDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, 30 km/h south wind, alpine temperature -13 C.

TUESDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 30 km/h southwest wind, alpine temperature -12 C.

WEDNESDAY: Increasing clouds with no precipitation, 20 km/h south wind, alpine temperature -12 C.

THURSDAY: Cloudy with snowfall, accumulation 10 to 15 cm, 40 km/h southwest wind, alpine temperature -7 C.

Avalanche Summary

A natural avalanche cycle was observed within the storm snow on Sunday. It is anticipated that this natural cycle continued into Monday. Naturally-triggered avalanche activity may taper into Tuesday but the likelihood of humans triggering the storm snow remains elevated.

Snowpack Summary

Over 80 cm of snow has accumulated since the weekend, with more snow forecast into Tuesday. Storm slabs likely exist in sheltered terrain. In wind-exposed terrain, strong southerly wind during the storm has likely redistributed some of the storm snow, forming thick slabs in lee terrain features and otherwise wind-pressed snow.

The storm snow overlies a weak layer formed during the cold spell in late December. The weak layer consists of sugary faceted grains as well as potentially feathery surface hoar found in areas sheltered from the wind. In high-elevation terrain exposed to the wind, the snow likely overlies a hard wind-affected surface.

A weak layer of faceted grains may be found above a widespread melt-freeze crust that formed in early December. This layer is likely found anywhere from 100 to 250 cm deep. This layer was the culprit of large, destructive avalanches in December. It has been most reactive between 1700 and 2100 m.

The lower snowpack is well-settled and strong.

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Stick to simple terrain and be aware of what is above you at all times.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.