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Avalanche Forecast

Archived

Jan 21st, 2022–Jan 22nd, 2022

Alpine
Natural avalanches possible, human triggered probable.
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

Jasper.

Forecasted inversion may increase sensitivity of avalanche problems at tree line and in the alpine on Saturday.

Weather Forecast

Relatively warm high pressure establishing through the weekend.

Saturday: Mix of sun and cloud.  Freezing level to 1500m. Alpine high -5 C. Winds west light.

Sunday: Mix of sun and cloud. Freezing level to 1600m.  Alpine high -4 C, low -8 C.  Winds west light.

Monday: Isolated flurries.  Freezing level valley bottom.  Alpine high -6 C, low -10 C.

Snowpack Summary

Previous N and present SW winds adding to wind slabs ALP and open TL. The mid-pack is highly faceted with active persistent weak layers from Dec. Interfaces within the facets found down ~30cm and ~60cm. These layers have varied sensitivity but if triggered can build large, destructive avalanches. Cornices are building.

Avalanche Summary

Several large avalanches were observed on Tuesday around the Churchill Range to sz 2.5 in the alpine - some running to ground. Patrol south on Thursday noted no new activity in the poor lighting but significant wind effect and drifting evident at all elevations. Uncertainty exists re sensitivity of our slab problem in the alpine and at tree line.

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.