Avalanche Forecast

Avalanche activity has continued throughout the week, as storm snow kept stacking up. Activity included storm slabs, wind slabs in wind loaded features and loose dry avalanches from steep sheltered terrain.

Natural and human triggered avalanches continue to be reported, mostly to size 2. Most avalanche activity is isolated to the storm snow or old/new interface, while several larger natural slab avalanches were reported to size 3.5 likely failing on the buried facets and surface hoar layers.

Deep persistent slab avalanche reports continue to trickle in over the week, to size 3. This evidence indicates the low probability but very high consequence weak basal snowpack is still active. Avalanches have occurred on all aspects and generally between 2200 m and 2800 m in elevation. Reports commonly noted the variation in depth - indicating that areas where the snowpack is shallow and rocky, or where it varies from thick to thin rapidly are still to be avoided. A fatal size 3 avalanche occurred near Invermere on Wednesday, which is directly adjacent to this forecast region.

Storm snow from this week has been redistributed by recent southwest winds into deeper deposits on north and east facing aspects. Current easterly winds are expected to build deposits on west facing slopes as well, resulting in variable wind loading patterns. This storm snow sits over wind effected surfaces, a thin sun crust on steep south facing slopes.

Around 50-90 cm deep a layer of small surface hoar exists in lower elevation sheltered areas. Elsewhere heavily wind effected surfaces exist, with faceted (sugary) snow from the late February Arctic blast.

Another small layer of surface hoar is buried 70-130 cm deep from mid February. This layer is most likely found around treeline elevations in areas sheltered from the wind. These two layers have shown reactivity, producing avalanches and concerning test results. The remainder of the mid-snowpack is generally strong.

A layer of large and weak facets that formed in November is deeply buried. Found near the base of the snowpack it is very slow to gain strength. The likelihood of human triggering this layer is currently low given its depth. However deep persistent slab avalanches continue to occurr, confirming it is still best to avoid steep, thin and rocky slopes at alpine and upper treeline elevations.

Saturday Night

Light southeast winds, gusting moderate. Freezing levels below valley bottom.

Sunday

Mostly sunny, especially in the north, with cloudy periods elsewhere. Moderate southeast winds ease over the day Freezing levels below 500 m, alpine high of -8 °C.

Monday

A mix of sun and cloud. Light southerly winds. Freezing levels around 800 m in the south, alpine high of -5 °C. Light snowfall possible in the afternoon.

Tuesday

Mostly cloudy with moderate southwest winds. Freezing levels rise to 1000 m. Alpine high temperature of -3 °C. Flurries in most areas.

More details can be found in the Mountain Weather Forecast.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Minimize exposure to sun-exposed slopes when the solar radiation is strong.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.