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

Mar 12th, 2025–Mar 13th, 2025

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

Regions

Purcells, East Purcell, St. Mary.

A persistent weak layer is in the snowpack, which means large avalanches are a concern.

Avoid large connected snow slopes, convexities and rocky areas.

Confidence

Moderate

Avalanche Summary

On Tuesday: Avalanche control happened in the region and produced large avalanches (up to size 3.5). The happened on north and east aspects in the alpine.

On Monday: There was extensive avalanche activity in the region. Large storm slab and wind slab avalanches occurred, with some stepping down to weak layers that are deeper in the snowpack, causing a persistent slab.

Snowpack Summary

Up to 20 cm of low density snow has been moderately redistributed by the wind in the alpine. This sits on a sun crust on solar aspects, and surface hoar or facets in sheltered areas or north aspects. Below treeline, a new surface crust likely exists from strong sunshine yesterday.

A few weak layers consisting of a crust, facets or surface hoar from February and January remain a concern, buried 30 to 60 cm.

A layer of facets from early December is buried 70 to 120 cm. In many areas, facets or depth hoar exist at the base of the snowpack. These deeper layers are not currently creating an avalanche problem.

Weather Summary

Wednesday Night

Mainly cloudy, with up to 5 cm of snow. 10 to 30 km/h southwest ridgetop winds. Treeline temperature -4 °C.

Thursday

Mainly cloudy, with 3 to 8 cm of snow. 20 to 50 km/h southwest ridgetop winds. Treeline temperature -3 °C.

Friday

A mix of sun and clouds, with flurries. 10 to 25 km/h southwest ridgetop winds. Treeline temperature -5 °C.

Saturday

A mix of sun and cloud, with isolated flurries. 10 to 30 km/h southwest ridgetop winds. Treeline temperature -3 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
  • Avoid steep, rocky, and wind-affected areas where triggering slabs is more 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.

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.