Snowfall amounts overnight are uncertain. We are also unsure of when and where the sun will shine. Solar radiation on dry storm snow is a concern for increased avalanche activity.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Light winds and 5-10 cm of new snow overnight. Winds becoming moderate from the west during the day on Saturday as a weak ridge of high pressure builds after the storm. There may be some sunny breaks Saturday afternoon, but more likely to clear overnight. Freezing levels bouncing between valley bottoms and 1400 metres. Mostly sunny on Sunday with light winds and freezing levels up to 1200 metres. Cloudy with increasing southwest winds on Monday.
Avalanche Summary
On Thursday we had reports of natural storm slab avalanches up to size 2.0 and explosives controlled avalanches up to size 2.5. On Wednesday there were reports of natural cornice falls up to size 2.5, and explosives control released slab avalanches up to size 2.5. Most of the slab avalanches were in the alpine on east aspects. I suspect that new wind slabs and storms slabs were easy to trigger in the alpine on Friday.
Snowpack Summary
There has been 20-30 cm of new snow in the past few days that has added to the recent storm slab above the buried crust. About 30-60 cm below the surface, you'll likely find a melt freeze crust which exists in most places except for in high elevation shaded terrain. In general there seems to be a reasonable bond between the crust and the overlying snow. I'd still keep an eye on this interface as it has become reactive on some features. If the sun comes out this weekend, periods of strong solar radiation may increase the likelihood of triggering the storm slab. In isolated areas there may be a weak layer of surface hoar at the storm snow/crust interface that is touchy to human triggers and may result in wide propagations. The early January surface hoar/ facet layer is typically down 70-120 cm. Avalanche activity at this interface has tapered-off over the past week, but I'd be reluctant to trust this potentially destructive layer just yet. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.
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.
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.
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.