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Avalanche Forecast

Archived

Jan 13th, 2026–Jan 14th, 2026

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
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.
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.

There is uncertainty on how prolonged warming will impact an already wet and weak snowpack.

Stick to simple, non-avalanche terrain and avoid exposure to overhead hazard.

Confidence

Moderate

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

Avalanche Summary

On Monday, several natural and human-triggered storm slabs (size 1-2) were observed on a variety of aspects and elevations. Observations were limited by stormy weather.

Preliminary reports on Tuesday indicate that a natural avalanche cycle occurred as freezing levels rose to near mountain top.

Looking forward to Wednesday, warm temperatures and sun will continue to destabilize an already weak snowpack.

Snowpack Summary

Rain and warm temperatures have created a wet snow surface to at least 2200 m. A weak crust may form on the surface from clear skies overnight. At upper elevations, up to 25 cm of recent storm snow has been redistributed by strong southwest winds.

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 and warm temperatures 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

Tuesday Night
Partly cloudy. 30 km/h west ridgetop wind. Treeline temperature 1 °C. Freezing level 3200 m.

Wednesday
Sunny. 50 km/h west ridgetop wind. Treeline temperature 0 °C. Freezing level 3200 m.

Thursday
Sunny. 40 km/h northwest ridgetop wind. Treeline temperature -2 °C. Freezing level 1200 m.

Friday
Sunny. 20 km/h northwest ridgetop wind. Treeline temperature -4 °C. Freezing level 300 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • In times of uncertainty, conservative terrain choices are our best defense.
  • A moist or wet snow surface, pinwheeling, and natural avalanches are all indicators of a weakening snowpack.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

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.