Regions
Kootenay Boundary.
Weather Forecast
A ridge of high pressure will continue to keep the region dry, and sunny through Tuesday. Ridgetop winds are light from the SE. Freezing levels near 1100m dropping to valley bottom overnight. The pattern will start to change on Wednesday afternoon. Light snow amounts are expected with freezing levels near 1200m. Alpine temperatures could drop to -9, and treeline temps may hover near -6. Light snow amounts may spread across the region on Thursday with freezing levels possibly reaching 1500m.
Avalanche Summary
One notable size 2 skier triggered avalanche occurred outside the ski area boundary near Whitewater. This was on a North aspect @1985m. The crown depth was reportedly 40-60cms, 50 wide and running 150m down slope. 2 skiers were involved, and sustained no injuries. Other observations from around the region includes small surface sluffing from steep North facing aspects.
Snowpack Summary
Temperatures dropped below freezing again Sunday night, and persisted through the day at higher elevations. Crusts have been forming due to the melt and freeze cycle for the past few days. There is still dry snow on northerly aspects at higher elevations. Sun crusts have developed on steep solar aspects. Pin-wheeling and other signs of moist snow have been observed on solar aspects at and above treeline At treeline and below treeline surface faceting and surface hoar growth (up to 15mm) are forming; especially on shady aspects in sheltered locations. This may become future layers of concern once buried. Steep planar slopes with shallow snowpacks are the most suspect. The recent storm snow layer is about 30-50 cm thick and is quite variable across the region. There are a couple of thin crusts buried below the storm snow that have been producing moderate to hard shears in tests. Some areas are still getting sudden planar shears on the mid-December surface hoar layer.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.