Regions
South Coast Inland.
The recent storm snow is expected to be reactive at higher elevations, especially in wind loaded terrain. Extra caution is needed around steep sun exposed slopes on Sunday if the sun is shining for extended periods of time.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Sunday
Weather Forecast
Unsettled conditions are expected on Sunday with a mix of sun and cloud as well as the possibility of isolated flurries, especially in the south of the region. Alpine wind is expected to be moderate from the north. Freezing levels are forecast to fall to around 600 m Saturday overnight and reach around 1300 m Sunday afternoon. Mostly sunny conditions are expected on Monday with light alpine wind and freezing levels reaching around 1700 m in the afternoon. A mix of sun and cloud is currently forecast for Tuesday with freezing levels reaching around 1900 m and moderate alpine wind from the south.
Avalanche Summary
No new avalanches were reported on Friday. On Thursday, storm slabs up to size 3.5 were observed in the north of the region failing up to 100 cm deep. A size 2.5 wind slab was observed on a northeast aspect at 2300 m which failed down 100 cm and ran 1 km. Numerous solar triggered loose wet and loose dry avalanches were also reported. There have been no recent avalanches reported from the Coquihalla area or south of the region.On Sunday, the recent storm snow is expected to remain reactive to human triggering at higher elevations, especially in wind loaded terrain. Natural solar triggered sluffing is expected from steep sun exposed slopes. Natural wind slab avalanches and cornice releases are also possible when the sun is at its strongest.
Snowpack Summary
A new crust has formed on all aspects below 1800 m and on all sun exposed slopes. Dry snow is being reported on north aspects in the alpine where 40-60 cm has accumulated over the past week. On sun exposed slopes and at lower elevations, several crusts likely exist in the upper snowpack. In the north of the region, the February persistent weak layers may still be found in the alpine and are down 100-140cm. They include a buried surface hoar layer as well as a crust/facet layer. In the southern parts of the region, the mid and lower snowpack are generally well settled and strong.
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.
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.