Regions
Kootenay Boundary.
As temperatures continue to warm, pay particular attention to slopes that are being affected by the sun.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
FRIDAY NIGHT: Cloudy with clear periods. Alpine low temperature -5C. Light west winds at ridgetops.SATURDAY: Cloudy with sunny periods. Alpine temperature reaching -2C. Light west winds at ridgetops. Freezing level between 1800m - 2000m.SUNDAY: Mix of sun and clouds. Alpine temperature around 0C. Light west winds at ridgetops. Freezing level between 2000m - 2300m. No overnight freeze expected.MONDAY: Mainly sunny. Alpine high temperature +4C.Light west winds at ridgetops. Freezing level between 2500m - 2800m. No overnight freeze expected.
Avalanche Summary
Numerous small (up to size 1.5) wind slabs were triggered by skiers on Thursday on various lee aspects at treeline and above. The sun has already affected the snow on steep south-facing slopes and triggered small loose wet avalanches at lower elevations. Natural and human triggered loose wet avalanches are likely with tomorrow's strong sun and steadily rising freezing level.
Snowpack Summary
In the last week 25-40 cm of storm snow has fallen which is becoming moist on aspects that have seen the strong March sun. Recent winds have switched from north to west to south leaving wind affected snow on a variety of aspects, especially on features near ridgetops and open areas at treeline. Various surfaces are hidden under the recent storm snow such as sun crusts on southerly slopes, hard wind-affected snow in exposed locations and soft faceted snow in sheltered areas.Two weak layers that mainly consist of surface hoar are buried in the snowpack between 55 and 90 cm deep, these were buried in mid-February and early-February. The layers may be associated with a melt-freeze crust on southerly aspects. Although no recent avalanche activity has been reported on these layers, they may become a concern as the warming progresses.
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.