Watch out for lingering pockets of wind slab at treeline and in the alpine.
Confidence
High - Due to the number and quality of field observations
Weather Forecast
WEDNESDAY: partly cloudy, light southwesterly winds, 1500m freezing level with an inversion and above freezing level extending into the alpine. THURSDAY: mainly sunny, light southwest winds, freezing level rising to 2500m. FRIDAY: light snow through the day, light south winds, freezing level 2000m.
Avalanche Summary
Isolated artificially and naturally triggered storm slab, wind slab and cornice avalanches continue to be reported. Storm slab avalanches are expected to be remain reactive to human-triggering, especially if the sun pokes out. Cornices are reported to large and fragile, and may fail under the weight of a person.
Snowpack Summary
The recent storm snow continues to settle and gain strength, however, some lingering mid storm instabilities are still reactive to ski cutting in steeper terrain features. Ongoing southeast through southwest winds have been loading lee features in the alpine and at treeline and cornices are large and fragile. A thin breakable crust may cap moist snow on slopes that see direct sun. Several crusts can be found in the upper meter depending on elevation and aspect. The upper snow pack is sitting on a more widespread and thicker crust that extends into the alpine. In most places this crust is bridging a layer of surface hoar buried in early January. It is becoming increasingly hard to make this layer fail in snowpack tests and triggering an avalanche on it is unlikely.
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.