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Avalanche Forecast

Archived

Dec 10th, 2021–Dec 11th, 2021

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

Little Yoho.

Forecasted snow and strong winds will increase the avalanche hazard at upper elevations.

Weather Forecast

A Pacific frontal low will move East to the Rockies early Saturday bringing strong Westerly winds and 15 to 30cm of snow to the forecast region by the end of the weekend. Freezing levels will remain below valley bottom.

Snowpack Summary

15-30 cm of snow overlays the Dec 2 rain crust. This crust disappears between 2100-2250 m. At treeline and above, moderate winds have developed soft slabs in immediate leeward slopes. The weak Nov 5 crust/facet interface is present near the ground. We expect further wind slab development at upper elevations through the day Saturday.

Avalanche Summary

No new avalanche activity observed or reported Friday. Forecasted snow and strong winds Saturday will likely increase natural avalanche activity at upper elevations.

Confidence

Problems

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.

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.