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Avalanche Forecast

Archived

Jan 12th, 2023–Jan 13th, 2023

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

Regions

Kootenay Boundary, Bonnington, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir.

Continually assess the snowpack for signs of instability with changing weather conditions. Expect hazard to increase as snow accumulates and freezing levels rise.

Confidence

Moderate

Avalanche Summary

A number of small storm slab avalanches have occurred over the previous week, failing on a recently buried layer of surface hoar.

Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

Expect continued surface slab development throughout the day with forecast snow and wind. Roughly 40 cm of recent snow has buried a layer of surface hoar in wind-sheltered terrain, primarily at the treeline and below.

A melt-freeze crust is buried by roughly 70 to 90 cm. This crust ranges from 2 cm at higher elevations to 10 cm at lower elevations. Below the crust, the mid-snowpack is generally well consolidated.

A weak layer of facets and a crust near the bottom of the snowpack continues to be a concern.

Treeline snow depths are roughly 160 to 220 cm.

Weather Summary

Thursday night

Cloudy with snow, 5 to 10 cm. Moderate south ridgetop winds. Treeline temperatures around 0 C. Freezing levels 2000 m by early Friday morning.

Friday

Cloudy with snow, 5 to 10 cm. Moderate to strong south ridgetop winds. Treeline temperatures around 0 C. Freezing levels 2000 m.

Saturday

Cloudy with snow, 10 to 15 cm overnight and 5 to 10 cm throughout the day. Moderate south ridgetop winds. Treeline temperatures around 0 C. Freezing levels 1600 m.

Sunday

Cloudy with light snow, 2 to 10 cm. Light south ridgetop winds. Treeline temperatures 0 to -5 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for fresh storm slabs building throughout the day.
  • Closely monitor how the new snow is bonding to the old surface.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.