Surface slabs from yesterday's storm overlie a warm, Spring snowpack. Last night was the first decent freeze at tree-line in several days.
Weather Forecast
Mainly cloudy today with flurries, freezing levels staying around 1800m, and light to gusting moderate SW winds. More of the same tomorrow, with 5-10cm of snow in total from Tuesday morning to Wednesday night. Things will change dramatically on Thursday, with freezing levels rocketing to 3600m, sunshine, and light winds.
Snowpack Summary
Up to 15cm of snow fell overnight at 1900m. The new snow is insulating a moist snowpack and likely formed new storm slabs in immediate lee areas. The rain at lower elevations prevented a solid crust recovery and the snowpack is isothermal. Multiple crusts in the top meter of the snowpack provide sliding surfaces, especially on solar aspects.
Avalanche Summary
The parade of moist and wet avalanches continued yesterday with the rain. Numerous moist and wet avalanches, both loose and slab, were observed throughout the highway corridor. These slides are pushing very heavy, dense debris and are digging down to ground by the time they reach the valley. A moist size 3 was observed from Perley Rock yesterday.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.