Regions
Kootenay Boundary.
Warm air temperatures with strong afternoon sun may destabilize the upper snowpack on south-facing slopes. Use extra caution on sun exposed slopes during the afternoon.
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Warm and sunny is the theme for the next 3 days. On Sunday, mainly sunny conditions are expected with freezing levels reaching around 2300m. Alpine winds are expected to be moderate from the NW. On Monday, full sun is expected with freezing levels reaching upwards of 2500m. Alpine winds are again expected to be moderate from the NW. Conditions are currently forecast to be the same on Tuesday morning with increasing cloudiness during the afternoon. It currently looks like the region can expect snowfall on Wednesday.
Avalanche Summary
On Tuesday and Wednesday there were reports of small wind slabs being triggered by skiers and explosives. On Friday, natural sun-triggered sluffing was reported from steep sun-exposed slopes. As it warms and the amount of sun increases on Sunday, it may become easier to trigger the thin old pockets of wind slabs. During the afternoon it may be possible to trigger sluffing from steep sun-exposed slopes.
Snowpack Summary
Shady and sheltered slopes have 5-15 cm of snow from earlier in the week. Ongoing winds have redistributed this new snow in wind-exposed terrain resulting in a highly variable snow surface and the formation of thin wind slabs in leeward features. Steep sun-exposed slopes have a thin new sun crust on the surface. The most prominent feature in the snowpack is the thick late-Feb crust, down 5-30 cm. This crust is supportive all the way to ridge crest and is effectively "capping" the snowpack, keeping riders from stressing any deeper weak layers. There are still weak layers below this crust that we'll continue to monitor, but for now these layers are dormant. We would likely need significant warming and/or heavy loading to re-activate them.
Problems
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.