Avalanche Forecast

Archived

Mar 16th, 2025–Mar 17th, 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 unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Purcells, East Purcell, St. Mary.

Stay vigilant, as conditions may change rapidly.

Expect significant variability based on elevation, aspect, and exposure to wind and sun.

Confidence

Moderate

Avalanche Summary

Fri: Several large to very large (size 2-3) persistent slab avalanches occurred in the region. All of them initiated in the alpine.

Thurs: A large (size 2) naturally-triggered persistent slab near Invermere and a size 2.5 persistent slab near Kimberley were observed.

Tues: Avalanche control produced large avalanches (up to size 3.5) in the central-western part of the region.

Looking forward: Wind slabs and persistent slabs are expected to remain triggerable on Sunday.

Snowpack Summary

30 - 50 cm of new snow accumulated in the region over the last few days. This snow covers a crust on sunny slopes and lower elevations, and surface hoar or facets on sheltered and shady upper elevations. Alpine and treeline areas have experienced southwesterly winds that built slabs on lee north and east-facing slopes.

Several persistent weak layers consisting of a crust, facets or surface hoar from February and January remain a concern, buried 50 to 100 cm. In many areas, facets or depth hoar also make up the base of the snowpack.

Weather Summary

Sunday Night

Partly cloudy with isolated flurries up to 2 cm. 15 to 30 km/h west ridgetop winds. Treeline temperature -9 °C.

Monday

Mostly sunny. 10 to 25 km/h southwest ridgetop winds. Treeline temperature -5 °C.

Tuesday

Mostly sunny. 10 to 20 km/h west ridgetop winds. Treeline temperature -6 °C.

Wednesday

Sunny. 10 to 25 km/h south ridgetop winds. Treeline temperature -1 °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.
If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.