Avalanche Forecast

Archived

Dec 29th, 2021–Dec 30th, 2021

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

Jasper.

Temperatures have moderated slightly on the Icefields Parkway but extra layers & a cautious attitude is still recommended.

Wind slab is our primary concern however deep persistent slabs have been triggered by cornices & surface avalanches recently.

Weather Forecast

Thursday: A mix of sun and cloud.

Alpine temp: high -20 C. Weak alpine inversion.

Wind: West 10km/h

Friday: A mix of sun and cloud.

Alpine temp: low -23 high -20 C. Weak alpine inversion.

Wind West: 10 km/h

Saturday: Mainly Cloudy with isolated flurries. Trace Precipitation

Alpine high -17

Wind South West 20km/h

Snowpack Summary

Cold temps are faceting the upper snowpack but pockets of wind slab are still present on all aspects at & above tree line. The mid-pack is supportive with the dec 1 crust interface down approx. 40 cm in most locations. Basal faceting continues below the Nov 5 crust potentially amplifying the deep persistent slab problem.

Avalanche Summary

A natural size 2.5 avalanche was observed on Mt. Wilcox during a road patrol today. Estimated date Dec 27th. This avalanche appears to have started as a wind slab, stepping down to deep persistent slab mid path. View min report here

Marmot Basin reported a similar observation with a natural cornice failure triggering deep persistent slab Dec 24.

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.

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.

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.