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Avalanche Forecast

Archived

Jan 1st, 2022–Jan 2nd, 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 possible, human triggered probable.
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

North Columbia.

Avalanche danger will increase over the day as new snow and strong winds form reactive slabs over a weak snow surface. Approach wind loaded features with caution.

Confidence

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

Weather Forecast

An active front shifts south bringing moderate snowfall with very strong winds.

SATURDAY NIGHT: Continued light snowfall, 5-10cm with strong to extreme southwest winds. 

SUNDAY: Moderate southeast winds increase over the day to strong southerlies. 10-20cm possible over the day. Alpine high of -15. 

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

TUESDAY: Chance of flurries with light southeast winds. Alpine high of -15. 

Avalanche Summary

Persistent slab avalanches were produced by explosive control work yesterday up to size 3. These slabs failed on the early December crust/facet interface up to 100cm deep. Several large and destructive avalanches have been naturally and skier triggered in the over the last week up to size 3. Each had wide propagation and ran several hundred metres. The avalanches were up to 150cm deep and were triggered in a rocky and thin area. This layer is still extremely concerning and will likely be for most of the season.

In the past 3 days, several wind slabs up to size 2 have been triggered by riders on northerly and southerly aspects at treeline and above. Several natural cornice failures were also observed on all aspects. Cornices are able to effect deeply buried weak layers, navigate around them (on ridgelines, and on slopes below them) with care. 

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

Snowpack Summary

New snowfall and wind continues to redistribute recent snow into deeper deposits on north and east aspects at treeline and above. These new slabs will form over faceted and wind effected surfaces, creating a poor bond and reactive slabs. 

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. Although avalanche activity hasn't been prominent on this layer, it has been reactive in snowpack tests.

The crust formed by the early December rain event sits 100-150cm deep and is found up to 2200m in the North 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. This layer has the potential to produce large and destructive avalanches if triggered. Recent activity in the North 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.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.

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.