Avalanche Forecast

Archived

Dec 27th, 2025–Dec 28th, 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.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

East Purcell, St. Mary.

Wind slabs have been reactive recently

Seek out good riding in sheltered terrain with no wind effect.

Confidence

Moderate

Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Avalanche Summary

On Friday:

Several size 1.5 to 2 naturally triggered wind slabs were observed in the alpine near Panorama on wind-loaded north through easterly aspects. (See photos)

Two size 1 cornices were triggered with explosives near Panorama.

On Thursday:

A naturally triggered size 2 wind slab was observed in steep alpine terrain off of Jackpine Mountain near Panorama

* If you are travelling in the mountains, please submit any observations to the Mountain Information Network.

Snowpack Summary

Recent snow, combined with forecast moderate shifting winds, is expected to form wind slabs on all aspects at upper elevations.

A persistent weak layer from mid-November, made up of a thick crust with overlying facets, and in some cases surface hoar, remains a lingering concern. In eastern parts of the region, it is buried around 110 cm deep, and up to 180 cm in western areas with a deeper snowpack. The likelihood of triggering this layer is low, but the consequences could be high.

Depth hoar is present at the base of the snowpack.

Weather Summary

Saturday Night
Clear skies. 30 km/h northwest ridgetop wind. Treeline temperature -16 °C.

Sunday
Sunny. 30 km/h northwest ridgetop wind. Treeline temperature -13 °C.

Monday
Mostly sunny. 30 km/h west ridgetop wind. Treeline temperature -9 °C.

Tuesday
Mostly sunny. 20 km/h west ridgetop wind. Treeline temperature -5 °C.

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.
Recent wind has varied in direction, so watch for wind slabs on all aspects.
Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and slopes above cliffs.

Problems

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.

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.