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Avalanche Forecast

Archived

Nov 30th, 2020–Dec 1st, 2020

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

Regions

Cariboos.

  

Lingering wind slabs may remain surprisingly reactive to human triggers in areas where they are sitting on top of a layer of small surface hoar.

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

  

MONDAY NIGHT: Clearing skies / Moderate, northwest ridgetop wind / alpine low temperature -15 / Freezing level valley bottom.

TUESDAY: Sunny / Light to moderate, northwest ridgetop wind / alpine high temperature -4 / Above freezing layer of air moving in late afternoon and creating a strong temperature inversion with warm air above roughly 2000 m.

WEDNESDAY: Sunny / Moderate, south ridgetop wind / alpine high temperature +1 / Strong inversion with an above freezing layer of air above 2000 m.

THURSDAY: Mix of sun and cloud / Moderate, southwest ridgetop wind / alpine high temperature +1 / Strong inversion with an above freezing layer of air above 2000 m.

Avalanche Summary

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

Snowpack Summary

  

50-80 cm. of recent storm snow and moderate to strong southwest winds formed widespread wind slabs. These slabs may be especially reactive to human triggers in areas where they are sitting on a layer of small surface hoar. There is a crust from early November now down approximately 75-125 cm. This crust has been observed with sugary facets above and below it. There are limited observations on this layer, but some test results indicate that it has the potential to be reactive to human triggering. Total snowpack depths are an average of 100-200 cm at upper elevations, tapering quickly at lower elevations. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid lee and cross-loaded terrain.

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.

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.