Avalanche Forecast

Archived

Mar 25th, 2025–Mar 26th, 2025

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Purcells, Dogtooth, East Purcell.

Rising temperatures are creating very dangerous avalanche conditions. Large, destructive natural avalanches are likely. Avoid avalanche terrain.

Confidence

High

Avalanche Summary

Natural persistent slab avalanche activity has been observed throughout the region over the last week. On Monday, a few size 2 to 2.5s were observed between Golden and Invermere. Smaller storm slabs were also reported in the Dogtooth area.

Looking forward, we can expect to see more large persistent slab avalanches as temperatures spike on Wednesday.

Snowpack Summary

Surfaces are becoming moist on all aspects as the freezing level climbs. Below lies a complex snowpack with several weak layers which are currently concerns for triggering persistent slab avalanches:

An interface from early March, 30 to 50 cm deep, consists of a crust on sunny slopes and lower elevations, and surface hoar or facets in sheltered, shaded upper elevations.
Persistent weak layers from February and January, including crusts, facets, and surface hoar, are buried 50 to 100 cm deep and remain a concern.
The bottom of the snowpack is composed of large facets, which are showing signs of becoming reactive again, with some very large avalanches recently failing on this layer.

Weather Summary

Tuesday night

Partly cloudy. 20 to 30 km/h southwest ridgetop winds. Treeline temperature +3 °C. Freezing level 2500 m.

Wednesday

Mostly sunny. 10 to 20 km/h southeast ridgetop winds. Treeline temperature +5 °C. Freezing level rising to 3000 m.

Thursday

Mostly cloudy with scattered flurries. 20 to 30 km/h southwest ridgetop winds. Treeline temperature 0 °C. Freezing level falling to 2000 m.

Friday

Mostly cloudy with scattered flurries. 10 to 20 km/h southeast ridgetop winds. Treeline temperature -2 °C. Freezing level 1000 to 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Cornice failures could trigger large and destructive avalanches.
Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.

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.

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.

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.