There is some uncertainty if we will have sun all day, or if there may be a band of high cloud for most of the morning. Strong solar radiation may result in loose wet avalanches and natural cornice falls.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Saturday
Weather Forecast
Mostly clear overnight with light westerly winds and freezing down to valley bottoms. On Saturday, mostly clear with light southwest winds and freezing levels rising to 1700 metres. Cloud and light precipitation developing by Sunday morning with freezing down to at least 1000 metres. On Sunday, cloudy with 3-5 cm of snow and freezing levels rising up to 1300 metres. Light snow and moderate northwest winds on Monday, before the next ridge of high pressure brings back the clear skies.
Avalanche Summary
On Thursday, we had reports of storm slab avalanches up to size 2.5 in isolated steep unskiable terrain. I suspect that storm slabs continued to be easy to trigger on Friday on shaded aspects, and loose moist or wet avalanches released naturally during periods of strong solar radiation.
Snowpack Summary
The dry new storm snow on Thursday settled with warm temperatures and periods of strong solar radiation. Moist snow was reported on solar aspects in the alpine, and up to at least 1800 metres on shaded aspects. There are several thin crusts in the upper snowpack on all but shaded north aspects. Expect a new surface crust to develop overnight with forecast freezing level dropping down to valley bottoms. The late February persistent weak layer continues to be a concern for wide propagations in isolated terrain, however it may take a large trigger like a cornice fall to initiate an avalanche. Watch for recent storm snow releasing as loose wet avalanches on steep solar aspects during periods of strong solar radiation and/or daytime warming.
Problems
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.
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.