Avalanche Forecast

Archived

Feb 28th, 2025–Mar 1st, 2025

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Skyrocketing alpine temperatures and reactive persistent slabs are a bad mix. Saturday will be a day to avoid avalanche terrain entirely, no matter how enticing it looks.

Confidence

Moderate

Avalanche Summary

A final 10 - 20 cm of new snow led to active avalanche conditions in the midweek, with a variety of triggers producing mainly small storm and wind slab releases. These ranged from 10 - 40 cm in depth while recent persistent slabs in the size 2 to 3.5 range, predominantly running on the late January crust, have featured 60 - 80 cm crowns. See the size 3.5 below. Persistent slab activity in particular is expected to resume or possibly intensify as warming tests the snowpack.

Snowpack Summary

A melt-freeze crust or moist snow now glazes the surface on solar aspects and, by Saturday, as high as mountaintop. High overnight freezing levels mean crust recovery may be weak. This process is affecting 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 while warming tests the snowpack.

Weather Summary

Friday Night

Clearing. 10 to 15 km/h southwest ridgetop winds. Freezing level rising to 2500 m.

Saturday

Sunny. 15 to 20 km/h southwest ridgetop wind. Freezing level to 3100 m. Treeline temperature 7 °C.

Sunday

Mainly sunny with cloud increasing. 10 to 15 km/h variable ridgetop wind. Freezing level falling from 2700 m to 2400 m. Treeline temperature 6 °C.

Monday

A mix of sun and cloud. 10 to 20 km/h northeast ridgetop wind. Freezing level to 1800 m. Treeline temperature 3 °C.

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.
Make conservative terrain choices and avoid overhead hazard.
Even brief periods of direct sun could produce natural avalanches.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.