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Avalanche Forecast

Archived

Dec 22nd, 2020–Dec 23rd, 2020

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

Jasper.

Ice climbers beware, Many avalanches, both loose dry and wind slabs were directly observed failing today on Mt Wilson. Even a small sluff can be bad news in a terrain trap.

Weather Forecast

A mix of sun and cloud for the next several days.

Winds will be generally light out of the West with cool nights -16 and seasonable temps -10 during the day.

No new snow expected.

Snowpack Summary

The snowpack continues to settle rapidly. NW winds continue to strip recently loaded lee slopes and build wind slabs in S-SE features. Decomposing surface hoar down 30cm to 50cm in sheltered locations treeline and below. The midpack is generally supportive with a weaker base consisting of facets and depth hoar. Avg depth is 65cm - 160cm depending

Avalanche Summary

A road patrol down to Saskatchewan crossing noted numerous wind slabs to size 2.5 out of West facing alpine features on Mt. Wilson along with several loose dry avalanches to Size 2 on west facing steep terrain. Back towards the Icefields, 3 Size 2 fresh wind slabs from reverse loading in the alpine were noted today.

Confidence

Due to the quality of field observations

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.

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.

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.