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Avalanche Forecast

Archived

Feb 8th, 2019–Feb 9th, 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 unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Columbia.

There is potential for triggering large avalanches at and below treeline 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

Moderate -

Weather Forecast

Cold, dry, arctic air continues to dominate the weather pattern for the foreseeable future.FRIDAY NIGHT: Freezing level at valley bottom, around -20 C in the alpine, potentially strong valley bottom wind event, light to moderate southeast wind in the alpine, trace of snow possible.SATURDAY: Scattered cloud cover at dawn with clouds steadily clearing through the day, freezing level at valley bottom, around -20 C in the alpine, light winds at most elevations, moderate east/southeast wind at ridgetop, no significant snowfall expected.SUNDAY: Clear skies at dawn with cloud cover increasing throughout the day, freezing level at valley bottom, around -20 C in the alpine, potentially strong valley bottom wind event, light southwest wind in the alpine, no significant snowfall expectedMONDAY: Scattered cloud cover, freezing level at valley bottom, around -20 C in the alpine, light variable wind at all elevations, no significant snowfall expected.

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 trigger remotely (from a distance). Human triggered avalanches size 1.5 to 2.5 were reported on Sunday, Monday, Tuesday, Wednesday and Thursday on a variety of aspects at treeline and below. There have also been a few reports of natural and skier triggered wind slab avalanches in the alpine size 1-2 in the past 3 days.

Snowpack Summary

20-70 cm of recent new snow sits on wind slab, surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. In many areas, recent winds have formed 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 40-90cm. 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 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.