Avalanche Forecast

Archived

Feb 26th, 2025–Feb 27th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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, Grohman, Kootenay Pass, Norns, Rossland, Ymir, Crawford.

Warming will seriously test the snowpack in the coming days and will likely produce destructive persistent slab avalanches. It might feel like spring, but the snowpack is far from settled.

Confidence

Moderate

Avalanche Summary

A mix of natural, remotely tiggered, and ski cut avalanches in the size 1 - 1.5 range were observed Tuesday, involving both the recent storm interface and deeper persistent weak layers. Visibility was limited, so the full extent of activity isn't certain.

Avalanches reached size 3.5 on Monday, with natural releases during periods of heavy snowfall and strong winds.

Activity of this type is expected to resume or even intensify as forecast warming tests the snowpack.

Snowpack Summary

By Thursday, a new melt-freeze crust should glaze the surface on solar aspects and below about 1700 m. The depth of affected snow should increase over the coming days and crust recovery may be weak. This process will affect the upper part of 30 to 50 cm of settling recent snow, which is wind affected at higher elevations and may overlie faceted snow or surface hoar where sheltered.

Two other key weak layers are present in the mid snowpack: a surface hoar or thin crust from mid-February buried 40-60 cm deep, and faceted snow/surface hoar/crust from late January buried 60-90 cm deep. These layers have been active during recent storms and are expected to produce avalanches as forecast warming tests the snowpack.

Weather Summary

Wednesday night

Mostly clear skies with possible valley cloud. 20 to 30 km/h southwest ridgetop winds, increasing. Treeline temperature -3 °C. Freezing level 1400 m with a possible above freezing layer around 2500 m.

Thursday

Mostly sunny with possible valley cloud. 20 to 30 km/h southwest ridgetop winds. Treeline temperature +4 °C. Freezing level rising to 2200 m, higher overnight.

Friday

Sunny. 10 to 20 km/h southwest ridgetop winds. Treeline temperature +5 °C. Freezing level rising to 2500 m.

Saturday

Sunny. 20 km/h southwest ridgetop wind. Treeline temperature +6 °C. Freezing level 2800 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
Use careful route-finding and stick to moderate angled slopes with low consequences.
Even brief periods of direct sun could produce natural avalanches.
Avoid exposure to overhead hazards when solar radiation is strong.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.