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Avalanche Forecast

Archived

Jan 9th, 2021–Jan 10th, 2021

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

Regions

Jasper.

Winds have diminished except for the very high alpine but the wind-slabs have formed from previous days. Natural avalanche activity has decreased yet conservative terrain selection is advised, assess every slope and human triggering remains possible.

Weather Forecast

Sunday: Mainly cloudy with isolated flurries. High -7. Wind SW: 20-40 km/h.

Monday: Flurries. 8 cm. Low -8, High -6. Wind SW: 25 km/h gusting to 80 km/h

Tuesday: Periods of snow. Accumulation: 16 cm. Low -10, High -5. Wind SW: 20 km/h gusting to 45 km/h.

Snowpack Summary

The top layer is 40cm of new snow from Jan 3rd which has settled down to 20-30cm in sheltered spots or was redistributed by SW winds into wind-slabs at higher elevations. It overlies a sporadically distributed surface hoar and facet layer down 40-70cm. The mid-pack is supportive except in shallow locations. The bottom is weak facets and depth hoar.

Avalanche Summary

Saturday's flight and weather station service the team did not observe any new avalanches with excellent visibility and lots of terrain covered. Wednesday's patrol to the Icefield's had one size 3, N aspect, high alpine, 1m thick and 300m wide on the backside of Mushroom peak being a wind-loaded spot.  Use Mountain Information Network to report.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Monday

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.