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Avalanche Forecast

Archived

Mar 18th, 2022–Mar 19th, 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 unlikely, human triggered possible.
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

Banff Yoho Kootenay.

A little windier Friday night and a little warmer on Saturday is keeping the hazard rating steady. We are keeping danger rating at moderate below treeline due to recent avalanche activity noted in Kootenay Park on Thursday.

Weather Forecast

Continued flurries for Saturday with a few cm's of accumulation and a mix of sun and cloud through the day. Winds will be in the moderate range out of the SW at ridge crests. Temperatures increase slightly with treeline temperatures ranging from -5 to -3 C and freezing levels reaching 1800 m before falling back down on Sunday.

Snowpack Summary

20-50 cm of recent snow forming fresh wind slabs in alpine and some treeline terrain with mod-strong SW winds. On solar aspects a variety of buried sun-crusts down 30-60 cm are producing moderate results in tests. In addition there is a buried temperature crust at lower elevations that exists on all aspects, and has been reactive 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 and extended 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.