Avalanche Forecast
Regions: East Purcell, Purcells, St. Mary.
Surface beneath the new snow varies, assess the bond as you change aspect and elevation.
Take extra care when transitioning into wind affected terrain.
Confidence
Moderate
Avalanche Summary
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.
Notably, on March 6th, one person was buried in an avalanche in Pedley Pass, just east of the forecast area. See details about that avalanche and a few nearby in these MINs.
Snowpack Summary
Up to 20 cm of low density snow has been moderately redistributed 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
Tuesday Night
A mix of sun and cloud, with isolated flurries. 10 to 20 km/h southwest ridgetop winds. Treeline temperature -6 °C.
Wednesday
Mainly cloudy, with isolated flurries. 10 to 20 km/h southwest ridgetop winds. Treeline temperature -3 °C.
Thursday
Mainly cloudy, with up to 5 cm of snow. 10 to 25 km/h south ridgetop winds. Treeline temperature 0 °C.
Friday
A mix of sun and clouds, with flurries. 10 to 25 km/h southwest ridgetop winds. Treeline temperature -4 °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.
- Pay attention to the wind; once it starts to blow, sensitive wind slabs are likely to form.
Avalanche Problems
Wind Slabs
The surface beneath the new snow varies from surface hoar, surface facets, or sun crust. Expect deeper deposits and more reactive slab in lee areas.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
Several persistent weak layers exist, with the most problematic ones lying 30 to 60 cm deep. These layers remain a concern where there is no thick, supportive crust near the surface.
Aspects: North, North East, East, West, North West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1.5 - 3