The new storm slab will be easy to trigger today, especially on solar aspects.
Weather Forecast
The cold front has passed, leaving us in the wake of unsettled, convective flurries for the day. Freezing levels should remain at 1600m or below and winds will be moderate from the west. A drying trend will take us into the weekend, but expect to have the occasional Spring convective flurry on Friday. Freezing levels will hover between 1200-1600m.
Snowpack Summary
15cm of warm, wet snow fell overnight with mod SW winds. This has formed a storm slab in the alpine and at tree-line elevations in lee features, both at ridge-top and on exposed slopes. The storm slab will be more reactive on solar aspects, as it will be sitting on a crust. Multiple crusts in the upper metre may promote step-down avalanches.
Avalanche Summary
No new avalanches were observed in the highway corridor yesterday, nor were there any noted by field crews up Perley Rock and Fidelity. Older debris was noted from several days previous, when temp's first warmed up.
Confidence
Wind effect is extremely variable
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.
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.
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.