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Avalanche Forecast

Archived

Jan 30th, 2022–Jan 31st, 2022

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

Regions

Little Yoho.

An upslope (NE flow) storm starts tonight giving us a 10-15 cm refresh of snow by Monday afternoon with a cooling trend. Expect smallish fresh windslabs that trigger easily and note the date (Jan 30), because a new weak layer is getting buried now.

Weather Forecast

Winds shift to a NE upslope flow overnight on Sunday with 10 cm expected by Monday morning under cooling temperatures as a cold front crosses the area making for blustery conditions. This should clear out by the end of Monday, leaving a maximum of 15 cm of snow in its wake. Temperatures continue to drop until Wednesday morning.

Snowpack Summary

10cm of new snow under an upslope flow will produce small, fresh windslabs and surface instabilities that bond poorly to the underlying surface of crust and facets (hint: new weak layer getting buried). Expect easy triggering of thin slabs. This storm is unlikely to wake up the deep facets, but they continue to lurk anywhere from 100-150 cm deep.

Avalanche Summary

No new avalanches observed or reported on Sunday. Over the past week we have received reports and observed a few avalanche to size 3 on the persistent weak layer. All of these avalanches were triggered by large loads (cornice).

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.