Confidence
Fair - Forecast snowfall amounts are uncertain on Sunday
Weather Forecast
Saturday night and Sunday: Moderate snowfall becoming light on Sunday / Moderate southwest winds becoming light and northwesterly with strong gusts / Freezing level at surfaceMonday: Light snowfall / Light west winds with strong gusts / Freezing level at 800mTuesday: A mix of sun and cloud with snowfall developing late in the day / Light southwest winds / Freezing level at 800m
Avalanche Summary
On Thursday and Friday there was a widespread natural avalanche cycle which included several size 3 slabs. Some released to ground below 1500m where the snowpack had become saturated by heavy rain. At higher elevations slabs released within the recent storm snow or on the surface hoar layer buried on March 10th.
Snowpack Summary
At treeline and above, light amounts of new snow overlie deep and cohesive storm slabs that formed with heavy snowfall, strong southwest winds and warm temperatures. Widespread cornice development has also taken place. At lower elevations rain penetrated the snowpack, and below 1400m the snowpack was reported to be isothermal. The recent storm snow overlies a weak layer of surface hoar or a sun crust that were buried on March 10th. Some areas had strong winds before the surface hoar was buried, so its distribution may be specific to sheltered and shaded terrain features. Some professionals are still expressing concern for the layer of surface hoar buried on February 12th. This interface is now well over 1.5m below the surface and triggering has become 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.