Avalanche Forecast

Moderate - Uncertainty is due to limitations in the field data.

Friday night: Clear, northerly wind 20-30 km/h, treeline temperatures around -10.

Saturday: Sunny, northwest wind 20-30 km/h, treeline temperatures around -12.

Sunday: Increasing cloud, flurries starting in the afternoon, light southwest wind, treeline temperatures around -12.

Monday: Flurries, up to 5 cm, light southerly wind, treeline temperatures around -12.

A few small skier controlled wind slabs have been reported at wind loaded ridgecrests, likely failing on shallow surface hoar and running on a near surface crust.

Last week a few natural avalanches are suspected to have run on the surface hoar 20-50 cm down, including a size 2.5 storm slab out of a northwest facing gully feature around 2000 m near Nelson.

The upper snowpack is composed of an arrangement of one or more crusts, varying with elevation and between areas within the region. The uppermost crust extends up to around 2000 m, ie. ridgetop in areas such as Rossland. In higher terrain, 10-15 cm of wind affected snow may sit over crust or large surface hoar crystals in wind sheltered areas above the crust elevation.

A layer of surface hoar may be found 20-50 cm below the surface in isolated areas in the north and east of the region. There was previous avalanche activity on this layer, but it seems at this point that most features that would run, have run on it already. Where it has been found in the most recent snow profiles, it has been producing moderate to hard planar test results but the crystals are observably rounding. We expect that this layer won't be a problem for too much longer...

A couple of crusts surrounded by weak faceted grains are buried deep within the snowpack. The upper layer is 80 to 130 cm deep and the lower is near the ground. A few large avalanches ran naturally on these layers earlier this month near Rossland. More recently, some large cornice falls have have been good slope testers, some triggering storm slabs but none stepped down to these deeper layers. While this is a good indicator for stability, the potential may linger for triggering a deep slab in steep, rocky, thin snowpack areas. 

• Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Surface hoar distribution is highly variable. Avoid generalizing your observations.
• When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.