Avalanche Forecast

Archived

Feb 21st, 2025–Feb 22nd, 2025

Alpine

Natural avalanches unlikely, human triggered possible.

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, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Purcells, Esplanade, Dogtooth, East Purcell, St. Mary, West Purcell.

Warming and stormy weather in the forecast have increased the likelihood of avalanche activity this weekend.

Confidence

Moderate

Avalanche Summary

Thursday, three persistent slabs (size 1.5 to 2.5) were observed in the alpine in various parts of the region. One was remotely triggered by a skier and the others occurred naturally.

Thursday & Wednesday, several small (size 1 to 1.5) dry loose avalanches were reported, with natural and human triggers all across the region.

Monday, a fatal avalanche incident occurred outside the forecast region near Golden. Click here for details.

Snowpack Summary

Overnight and through Saturday, up to 10 cm of new snow is expected in the western Purcells, less in the east. The storm will come with moderate to strong southwesterly winds, creating new wind slabs. This new snowfall will accumulate on top of 5 to 10 cm of existing snow covering a layer of surface hoar in sheltered areas, or a hard sun crust on sunny slopes. 20 to 40 cm below that, is a persistent weak layer of facets/surface hoar or a crust buried in late January. A weak layer of facets from early December is buried 60 to 120 cm from the surface. The base of the snowpack consists of facets or depth hoar in many areas.

Weather Summary

Friday Night

Cloudy with 1 to 5 cm of snow. 15 to 30 km/h southwest ridgetop wind. Treeline temperature -4 °C.

Saturday

Cloudy with 1 to 5 cm of snow. 30 to 50 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level rising to 2000 m.

Sunday

Cloudy with 0 to 7 cm of snow. 30 to 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level rising to 1900 m.

Monday

A mix of sun and cloud. 20 to 35 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level rising to 1700 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.
Avoid thin areas like rocky outcrops where you're most likely to trigger avalanches on deep weak layers.
Be mindful that deep instabilities are still present and have produced recent large avalanches.
Use ridges or ribs to avoid areas of wind-loaded snow.

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.