The intensity of Friday night's storm is uncertain. If snowfall amounts are higher than anticipated or if the storm persists throughout Saturday morning, the avalanche danger may be HIGH in the alpine.
Confidence
Fair - Intensity of incoming weather is uncertain on Friday
Weather Forecast
Overnight Friday and Saturday: Moderate snowfall on Friday night tapering to light snowfall on Saturday / Strong southwest winds switching to moderate and northwesterly / Freezing level at 1200mSunday: Trace amounts of snow with overcast skies / Moderate northeast winds / Freezing level at 1200mMonday: Mix of sun and cloud / Calm winds / Freezing level at 1200m
Avalanche Summary
Natural loose dry avalanches to size 2 ran within Wednesday's storm snow, and a size 2 wind slab was ski cut on a northeast alpine slope just below ridge crest. A size 2 natural slab avalanche was observed in a north facing gully feature at 2100m. The early April interface was the suspected culprit. Although recent snow may be gaining strength, I would expect another round of storm slab activity to occur in response to wind and snow forecast for Friday afternoon.
Snowpack Summary
At upper elevations moderate amounts of recent snow have been shifted into deeper windslabs by steady southwest winds. About 40-75cm below the surface you are likely to find a temperature/sun crust from early April's clear weather. At the same interface you may find a layer of spotty surface hoar on shaded alpine slopes above ~2400m. At lower elevations (below 1600m) rain has saturated the snowpack, and surfaces are either moist or refrozen (temperature depending).Recent snowfall combined with wind have made large cornices bigger and more likely to fail.
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.