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Avalanche Forecast

Archived

Jan 12th, 2026–Jan 13th, 2026

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

Regions

South Rockies, East Purcell, St. Mary, Bull.

New storm slabs are adding more load to buried persistent weak layers.

Don't let the fresh powder lure you into consequential terrain.

Confidence

Moderate

  • Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.

Avalanche Summary

Sunday

  • Explosives triggered a few size 1 slabs. They failed on a persistent weak layer of surface hoar below treeline.

Saturday

  • A few small wind slabs were ski cut at treeline and below treeline elevations. They failed on a buried layer of surface hoar.

  • A large (Size 2) naturally-triggered wind slab failed on a north-facing alpine slope.

Looking forward

  • We expect the danger to rise as precipitation accumulates on Monday night and temperatures rise.

Snowpack Summary

Storm snow combined with strong southwesterly winds is expected to continue building storm slabs on Monday night. These slabs are expected to be most reactive in wind-loaded areas

Around 40 to 60 cm of snow overlies a persistent weak layer of surface hoar in wind-sheltered terrain, and a sun crust on steep south-facing slopes. New storm snow may overload these layers, creating large avalanches.

A deep persistent weak layer consisting of a thick melt-freeze crust, with weak faceted snow and/or depth hoar, can be found near the ground in shallow snowpack areas.

Weather Summary

Monday Night
Cloudy. 5 to 10 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -2 °C. Freezing level 1500 m.

Tuesday
Cloudy. 0 to 3 mm of precipitation as snow or rain at treeline. 40 km/h west ridgetop wind. Treeline temperature 0 °C. Freezing level 1900 m.

Wednesday
Mostly sunny. 40 km/h west ridgetop wind. Treeline temperature 2 °C. Freezing level 3200 m.

Thursday
Sunny. 40 km/h northwest ridgetop wind. Treeline temperature -5 °C. Freezing level around 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Use increased caution at all elevations. Storm snow is forming touchy slabs.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Avoid freshly wind-loaded terrain features.
  • Avoid shallow snowpack areas, rocky outcrops, and steep terrain where triggering is most likely.

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.