New snowfall likely won't bond well to underlying snow surfaces. Expect old and new slabs on all aspects at higher elevations, loose dry snow in sheltered areas, and looming cornices on ridgelines. Use caution on solar slopes when the sun is out.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
FRIDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwesterly winds, alpine temperature -13 C, freezing level below valley bottom.SATURDAY: Sunny with late afternoon clouds, light northwesterly winds, alpine temperature -11 C, freezing level near 600 m.SUNDAY: Cloudy with early-morning snowfall then partly cloudy, accumulation 10 to 15 cm, strong westerly winds decreasing to light over the day, alpine temperature -11 C, freezing level near 600 m.MONDAY: Partly cloudy, light westerly winds, alpine temperature -10 C, freezing level 700 m.
Avalanche Summary
A large (size 3) natural cornice fall was observed, which likely released within the past few days. No slab was triggered beneath it. Otherwise, a small loose dry avalanche was triggered by a skier in steep terrain.Expect natural and human-triggered avalanche activity to increase with the storms and warming sunshine.
Snowpack Summary
Around 10 to 20 cm of storm snow fell with strong southerly winds, producing storm slabs on all aspects with deeper deposits found in lee features. This snow fell on previously wind-affected surfaces. The new snow may not bond well to these surfaces and could be reactive to both natural and human triggers.Deeper in the snowpack, a crust layer can be found on sun-exposed slopes below 1900 m, which allowed for slab avalanches to propagate widely over the past week.Even deeper, avalanche professionals are still monitoring the mid-January crust. This layer is now 150-200 cm deep, but a heavy trigger (such as a cornice fall) or the next major storm (loading and/or warming) could wake this layer up.Also make note of cornices at ridgeline. Variable winds in the past month have produced cornices on all aspects. They will become touchier as they grow in size, as temperatures rise, and as the sun packs a strong punch on clear days. Stand well back of them!
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.
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.