Avalanche Forecast

High - Confidence is due to a stable weather pattern with little change expected.

The ridge of high pressure is currently forecast to persist through Friday with the next storm system arriving Saturday night. 

Wednesday Night: Mainly clear with lingering valley cloud, light variable wind, treeline temperature around -10 °C.

Thursday: Mainly sunny with valley cloud, light SW wind, treeline high around -4 °C.

Friday: A mix of sun and cloud with lingering valley cloud, light to moderate SW wind, treeline high around -5 °C.

Saturday: Mainly cloudy with sunny breaks, moderate SW wind, treeline high around -4 °C.

On Tuesday, a natural size 1.5 persistent slab was reported on an E aspect at 1900 m in the Monashees north of Revelstoke failing down 30-45 cm. A natural size 2 cornice failure was reported on an E aspect at 2600 m. A slightly older size 2.5 wind slab was reported on a NE aspect at 2300 m in the eastern Selkirks. 

On Monday, wind/storm slabs avalanches up to size 1.5 were reported throughout the region; both intentionally and accidentally triggered by riders on convex features or steep slopes. Wind, warm temperatures and solar radiation have created a recent avalanche cycle (up to size 2) within the upper snowpack layers. Cornice falls were also suspected to have pulled out slabs. In the Selkirks, two very large deep persistent (size 2.5- 3) slab avalanches were also reported from various alpine aspects, which have released naturally on the December facet/crust layer. 

Over the past week, numerous very large (size 2.5-4.5) deep persistent slab avalanches occurred in both the Selkirks and Monashees. These avalanches failed on the early December facet/crust layer, typically 100-150 cm deep. This layer is likely to plague our snowpack for the remainder of the season and will be a low probability but extremely high consequence result if triggered.

The snow surface is highly variable and consists of a crust at lower elevations and on solar slopes into the alpine, wind affected surfaces and wind slabs in exposed terrain, and settling powder in sheltered areas on polar aspects. Ongoing surface hoar growth up to 10 mm has also been reported in sheltered areas which is expected to be most prominent at elevations near the top of the valley fog layer.

The top 50-100 cm of the snowpack has a variety of persistent layers that may or may not remain a problem. The most recent snowfall covered a layer of surface hoar which is now down 20-30 cm. A layer of facets and surface hoar from early January is now down around 40-60 cm. The layer of facets from the end of December is now down close to 1 m.

The primary weak layer that remains a widespread concern across the Columbia Mountains is a deeply buried crust/facet layer that formed in early December. It is typically down 100-150 cm, but as deep as 200 cm in wind-loaded terrain. There has been regular avalanche activity on this layer at all elevations for over a month, but we are now seeing decreasing evidence since the recent warming event. 

• Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Conditions may have improved, but be mindful that deep instabilities are still present.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.