Avalanche Forecast

Issued: Jan 13th, 2023 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Deep Persistent Slabs.

dsaly, Avalanche Canada

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

Continually assess the snowpack for signs of instability with dynamic weather conditions. Another 5-15 cm overnight will further add to the storm slab problem.

Summary

Confidence

Moderate

Avalanche Summary

A small (to size 1.5) storm slab avalanche cycle occurred early Friday morning near Kootenay Pass. 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

Upwards of 15 cm forecast for Saturday morning will add to recent storm snow. Expect ongoing surface slab development throughout the day with forecast snow and wind. 20-40 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 60-90 cm. This crust ranges from 2 cm at higher elevations to 10 cm at lower elevations. Below the crust, the mid-snowpack is settled and consolidated. A weak layer of facets and a crust near the bottom of the snowpack continue to be a concern. Treeline snow depths average 160-220 cm.

Weather Summary

Friday night

Snowfall with dropping temperatures, 5-15 cm overnight. Moderate to light south ridgetop winds. Treeline temperature below 0 C. Freezing level falling to 1500 m.

Saturday

Snowfall tapering through the day, localized 24-hr accumulations by Saturday at 4 pm up to 20 cm. Light south ridgetop winds. Treeline high temperature -1 C. Freezing level 1600 m.

Sunday

Snowfall increases through the day, 10 cm during the day followed by 10 cm overnight. Light to moderate south ridgetop winds. Treeline high temperature +1 C. Freezing level 1400 m.

Monday

Cloudy with isolated flurries. Light southwest ridgetop winds. Treeline high temperatures -3 C, freezing level below 1100 m.

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 slabs will be most reactive in localized areas with the deepest snowfall accumulations. A weak layer of surface hoar is reported 20-40 cm below recent snow. Expect storm slab reactivity to increase with elevation and exposure to the wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 1.5

Deep Persistent Slabs

Human triggering of deep weak layers remains possible in terrain with shallow, variable snowpacks. Where supportive to riders, a melt-freeze crust may be providing a bridging effect, making it more difficult to trigger deeper layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3.5

Valid until: Jan 14th, 2023 4:00PM