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Avalanche Forecast

Archived

Jan 2nd, 2022–Jan 3rd, 2022

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 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

South Columbia.

New snow and wind will form touchy storm slabs at all elevations. Keep terrain selection conservative until the storm snow gains strength.

In localised areas that receive more than 30cm of new snow, avalanche danger will be HIGH.

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

SUNDAY NIGHT: Strong southerly winds. 5-10cm possible overnight. Locally heavy accumulations are possible around Revelstoke, with up to 20cm overnight. 

MONDAY: Up to 5-10cm of snow, tapering off in the afternoon. Alpine high of -8 with light southwest winds.

TUESDAY: Chance of flurries with light southerly winds. Alpine high of -12. 

WEDNESDAY: Clearing skies, isolated flurries. Light southwest winds. Alpine high of -15. 

Avalanche Summary

Slabs in wind loaded features continue to be reactive to human triggers, producing avalanches up to size 2, on all aspects from the recent variable winds. As snowfall accumulates on top of these slabs they will be harder to identify. 

Cornice falls have triggered numerous slabs this week, as they land on the slope below. Navigate around cornices carefully (both on ridgelines and on the slopes below them with care - they are able to effect deeply buried weak layers. 

Several large and destructive persistent slab avalanches have been naturally and skier triggered in the Selkirks over the last week up to size 3.5, failing on the early December crust/facet interface. Each had wide propagation and ran several hundred metres. The avalanches were all triggered in a rocky and thin area. This layer is still extremely concerning and will likely be for most of the season.

We'd appreciate if you submit your observations to the Mountain Information Network, even just a photo.

Snowpack Summary

Storm snow with strong south-southwest winds continue to form new slabs with deeper deposits on north and east facing slopes. This load will be deposited on weak and wind effected surfaces - expect a poor bond and reactive conditions. 

A layer of weak surface hoar crystals can be found 30-50cm deep in sheltered terrain features at alpine and treeline elevations, and in open features like cut blocks below treeline. 

The crust formed by the early December rain event sits 100-150cm deep and is found up to 2400m in the South Columbia's. Weak and faceted grains sit above, creating a weak interface that is still reactive to human triggers. This layer is most reactive at treeline, and in areas where the snowpack thins and the weak interface is much closer to the surface. Recent activity in the Columbia's has been limited to explosive triggers - however the southern Selkirks have seen significant skier triggered activity on this layer to size 3.5.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
  • Avoid convexities, steep unsupported terrain and rocky outcroppings.

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.