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Avalanche Forecast

Archived

Mar 17th, 2022–Mar 18th, 2022

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 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.

Regions

Banff Yoho Kootenay.

Keeping danger rating at moderate below treeline due to recent avalanche activity noted in Kootenay Park today.

Weather Forecast

A weak ridge of high pressure builds for Friday. Lingering scattered flurries with only trace accumulations forecasted along the Continental Divide. Ridgetop winds SW in the 30-40 range. Freezing levels to reach 15-1700 m on Friday with good overnight recovery.

Snowpack Summary

20-50 cm of recent snow forming fresh wind slabs in alpine and some treeline terrain. On solar aspects a variety of buried sun-crusts exist down 30-60 cm that are producing moderate results with stability tests. In addition there is a buried temperature crust at lower elevations (below 1800 m that exists on all aspects) especially in Kootenay Park.

Avalanche Summary

Explosive control on Whymper and Simpson areas of Kootenay Park on Thursday produced small wind-slabs (up to size 2.5). Of note in Simpson area is when debris hit lower elevations (1800-1600 m) it triggered new slabs down 50 cm on a suspected temperature crust. Propagations on this layer were significant (up to 100 m).

Confidence

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.

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.