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Avalanche Forecast

Archived

Jan 14th, 2023–Jan 15th, 2023

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

Regions

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

Continually assess the snowpack for signs of instability. Be especially suspicious of shallow or rocky ridges and start zones.

Confidence

Moderate

Avalanche Summary

A widespread and reactive storm slab was reported around the region Friday. Skiers, vehicles, and explosives triggered slabs to size 2.5 with most crowns 30-50 cm deep, and many reported at treeline elevations 1700-2100 m (note poor visibility and no alpine observations).

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

Snowpack Summary

Flurries through Sunday may accumulate up to 15 cm. Fresh snow will cover a crust or moist snow up to 1900 cm. At higher elevations, 20-40 cm of recent snow has buried a layer of surface hoar in wind-sheltered terrain, primarily around treeline.

A facet/crust layer is down 40-90 cm (and 2-10 cm thick at TL elevation), and the mid-pack below is settled and consolidated. A concerning and weak layer of crust and facets makes up the basal snowpack. Treeline snow depths average 150-210 cm.

Weather Summary

Saturday night

Partly cloudy and isolated flurries. Light southeast ridgetop wind increasing into the morning. Treeline low temperature below -3 C. Freezing level falling below 1000 m.

Sunday

Flurries through the day, up to 15 mm in 24 hours, localized areas could accumulate 20 cm. Gusty south-southwest ridgetop wind. Treeline high temperature 0 C. Freezing falling to valley bottom.

Monday

Flurries through the day, up to 5 cm. Decreasing south ridgetop wind. Treeline high temperature -2 C. Freezing level 1300 m.

Tuesday

Cloudy with isolated flurries. Light southwest ridgetop wind. Treeline high temperature -3 C, freezing level below 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • 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.