Avalanche Forecast

Archived

Jan 10th, 2017–Jan 11th, 2017

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.

We switched our problems today to a Deep Persistent Slab, and a Wind Slab. The DPS problem is here for the long run, due to the weak faceted base. The WS problem is more dynamic; coming & going more often. Right now the N wind has created hard slabs.

Weather Forecast

Clear and cold for the next few days, with gradual warming starting for the weekend. Wednesday's temperatures will range from -16 to -25, with light winds out of the north (moderate winds up high). With the wind, the temperatures are brutal right now so be sure to bring tonnes of extra warm clothing and take care to not let yourself get too cold.

Snowpack Summary

18 cm of snow from the past 48-hr has been blown to smithereens by northern winds at treeline and above. This has produced a reverse loading pattern, with hard slabs in many starting zone areas overlying a weak, faceted snowpack with numerous instabilities in the lower half of the snowpack. This is today's snow profile from Bow Summit.

Avalanche Summary

SIze 1 skier accidental avalanche in a wind loaded gully at Bow Summit today, followed by our team getting a significant crack in the adjacent gully. Observed a size 2 natural avalanche in a leeward (from the north wind) feature on Observation Peak also. Lake Louise ski hill reported several hard to trigger slabs up to size 1, and lots of cracking.

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.