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Avalanche Forecast

Archived

Dec 13th, 2019–Dec 14th, 2019

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

Regions

Banff Yoho Kootenay.

Basal facets, crusts and depth hoar are everywhere. If you head into committing terrain, it will be a bit of a gamble whether you will trigger a slope as these layers are hard to predict. A classic rockies snowpack!

Weather Forecast

Lows of -10C in the valley Saturday AM and alpine temperatures around -15C. Mainly light NW winds and no significant snow is in the forecast for the next few days.

Snowpack Summary

Variable wind slabs from the past 2 days have formed mainly in the alpine. Beneath the recent 40-60 cm of storm snow, the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust is present up to 2500m and ~30 cm up from ground. Snowpack depths at treeline range from 80-160 cm.

Avalanche Summary

There were no avalanches reported Friday which is a big change from earlier in the week when there were many reports of either windslabs or deep persistent slabs with avalanche control and natural activity.

Confidence

Due to the number and quality of field observations

Problems

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.

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.