Regions
Kootenay Boundary.
There is the possibility that locally higher than forecast precipitation may fall in certain parts of the region. In the case of higher than forecast precipitation, the avalanche danger may be higher than indicated.
Confidence
Low - Due to the number of field observations
Weather Forecast
FRIDAY: Flurries, accumulation 10-15cm / Moderate to strong southwest wind / Alpine temperature -2 / Freezing level 1500mSATURDAY: Mainly cloudy with isolated flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -4 / Freezing level 1300mSUNDAY: Mix of sun and cloud / Light northwest wind / Alpine temperature -5 / Freezing level 1200m
Avalanche Summary
On Friday, the main concern is lingering wind slabs in high elevation north facing terrain and the possibility of large overhanging cornices releasing with overall warm temperatures over the coming days.
Snowpack Summary
The region is expected to have entered a period of widespread melt-freeze conditions on all aspects and elevations except for high north facing terrain where the surface snow is expected to remain dry. In high elevation terrain, recent strong southwest winds and new snowfall has formed wind slabs in leeward features. At lower elevations and on sun exposed slopes, there are likely moist or wet snow sitting on top of several well bonded crust layers in the upper snowpack. A rain crust which was buried on March 21 extends into the alpine is now down 60-80 cm. This crust was the bed surface for several avalanches during the solar cycle at the end of last week. At elevations above around 2100m, the February persistent weak layers may still be lingering down around 100-150cm and weak basal facets may still be lingering in shallow snowpack areas. These deep weak layers appear to have gone dormant but an isolated avalanche or cornice fall still has the potential to step down in the right conditions.
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.
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.
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.