Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Monday: Expect clouds to build through the afternoon, with light southerly winds and freezing levels to 1500m. Tuesday: Unsettled skies with occasional light flurries and freezing levels reaching 1500m. Winds stay southerly and begin to increase later in the day. Wednesday: Flurries developing through the day with accumulations of 10cm. Winds continue to blow moderate from the south with freezing levels reaching 1000m.
Avalanche Summary
Loose wet avalanches up to size 2.0 triggered by daytime heating have been reported, as well as isolated cornice releases to size 2.5. There was also 2 recent large natural avalanches reported; a size 3.0 from a northeast aspect in the Chilcotin area and a size 4.0 from a south aspect in the west side of the Duffey Lakes area.
Snowpack Summary
The warm temperatures have brought us into a spring melt freeze cycle with the surface snow softening with daytime warming on solar aspects then crusting overnight as temperatures dip back below freezing. Large cornices loom in at ridgecrest. Recent storm snow (now more than 72 hrs old) varies significantly throughout the region with southeast areas (Coquihalla) receiving up to 60cm of new snow, while places like the Duffey Lake have seen considerably less. The new snow is settling quickly and bonding well, with occasianl windslabs lurking in immediate lee locations. Crusts down around 60cm can be found on solar aspects in the Duffey Lake, Chilcotin, and down closer to 100cm in the Coquihalla. Deep, persistent weak layers buried in early February are variable in distribution across the region but remain a key concern. In recent snowpack analysis this layer remains well preserved as surface hoar on north aspects and is a suncrust, facet combo on solar aspects. On both aspects we have reports of clean sudden planar shears at an average depth of 150cm. Although the likelihood of triggering this layer has decreased, the potential for surprisingly large avalanches remains.
Problems
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.
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.
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.