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Avalanche Forecast

Archived

Dec 27th, 2020–Dec 28th, 2020

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

Regions

Cariboos.

  

A buried weak layer down 40-70 cm. continues to be a concern and has the potential to create large avalanches. This problem can be avoided through conservative terrain choices.

Confidence

Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

  

SUNDAY NIGHT: Cloudy / Light, west ridgetop wind / alpine low temperature -13 / Freezing level valley bottom.

MONDAY: Mostly cloudy with sunny periods / Light, west ridgetop wind / alpine high temperature -9 / Freezing level valley bottom.

TUESDAY: Mix of sun and cloud / Light, northwest ridgetop wind / alpine high temperature -11 / Freezing level valley bottom.

WEDNESDAY: Cloudy with isolated flurries; 0-3 cm. / Moderate, west ridgetop wind / alpine high temperature -9 / Freezing level valley bottom.

Avalanche Summary

On Monday there was a report of a human triggered avalanche that was suspected to have run on buried surface hoar. The MIN report can be view here.

Data in this region is very sparse. Please submit your observations to the Mountain Information Network. 

Snowpack Summary

10-15 cm of new snow with light winds over the last couple days.

Winds blowing from a variety of directions last week formed wind slabs in lee features at treeline and above.

An active weak layer is now down 40 to 70 cm. The distribution of this layer is variable. In some areas it's surface hoar and/or a crust; in others this layer may be difficult to find if it exists at all. Recent human triggered avalanches have been reported on this layer and have been most numerous in the areas between Blue River and Valemount.

There is a prominent crust near the base of the snowpack. This crust likely has weak facets above and/or below it. There have been no recent avalanches reported on this layer, but would be most likely to trigger in steep, shallow, rocky terrain, with a thin to thick snowpack.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be careful as you transition into wind affected terrain.

Problems

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.

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.