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Avalanche Forecast

Archived

Feb 7th, 2019–Feb 8th, 2019

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

Regions

North Columbia.

There is potential for triggering large avalanches treeline and below due to the presence of a persistent slab problem. Click here to see our Forecasters' Blog for a more detailed description of current conditions.

Confidence

High - The weather pattern is stable

Weather Forecast

FRIDAY - Mix of sun, cloud and isolated flurries/ moderate east wind / alpine temperature -18SATURDAY - Mainly sunny / moderate east wind / alpine high temperature near -20SUNDAY - Mix of sun and cloud / light east wind / alpine temperature -17

Avalanche Summary

A persistent weak layer that was buried in mid January continues to be reactive to human triggers. This layer is sensitive enough for avalanches to be triggered remotely (from a distance). Skier and snowmobile triggered avalanches up to size 2.5 were reported on Sunday, Monday, Tuesday and Thursday. This layer is the most reactive at treeline and below. This MIN report from Monday does a great job of illustrating the sensitivity of this weak layer.Human triggered avalanches failing on the mid January persistent weak layer have been reported almost daily for the past two weeks in the North Columbia region.

Snowpack Summary

30-80 cm of recent new snow sits on surface hoar (feathery crystals), facets (sugary snow), wind slabs and a crust on sun-exposed slopes. In many areas, recent winds have redistributed the new snow, forming wind slabs on all aspects due to shifting wind directions.The most notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 50-100 cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer is the most prominent at treeline and below, and continues to be produce avalanches.

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.