Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 6th, 2025–Jan 7th, 2025

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
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.

Regions

Purcells, Crawford, Dogtooth, East Purcell, Moyie, St. Mary, West Purcell.

Avoid rocky, thin, and shallow areas where triggering slabs is most likely

Give cornices a wide berth. Cornice failure may trigger persistent weak layers resulting in very large avalanches

Confidence

Moderate

Avalanche Summary

On Sunday, evidence of several natural persistent slab avalanches triggered by cornice failure were observed up to size 2. See this MIN for details and photos of two of these avalanches.

Avalanche control triggered a size 2 persistent slab avalanche in a treeline feature at 1900 m on a north aspect.

If you head out in the backcountry, let us know what you see by submitting a MIN!

Snowpack Summary

2 to 10 cm of low-density snow sits atop a variety of surfaces, including surface hoar and facets on northerly aspects, a thin breakable sun crust on southerly aspects, and isolated wind slabs in the alpine. In sheltered areas, 20 to 75 cm of snow continues to settle.

A weak layer buried in early December can be found down 50 to 90 cm. On shaded slopes, it consists of weak surface hoar or faceted crystals, while on south-facing slopes, it combines a sun crust with facets.

The snowpack base is composed of a thick crust and facets in many areas.

Weather Summary

Monday Night

Clear skies. 5 to 20 km/h southwest ridgetop wind. Treeline temperature -5 °C.

Tuesday

Mainly clear. 15 to 30 km/h west ridgetop wind. Treeline temperature -3 °C.

Wednesday

Partially cloudy with light flurries, 1 to 3 cm. 20 to 40 km/h west ridgetop wind. Treeline temperature -8 °C.

Thursday

A mix of sun and cloud. 15 to 30 km/h west ridgetop wind. Treeline temperature -7 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices.
  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

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.