Winter returns at upper elevations, time to get back in the mind set of choosing terrain carefully. JH
Weather Forecast
Saturday: A cold front passes over the area giving; moderate to strong SW wind; 10-15 cm of snow, and freezing levels spiking to TL as the front approaches then dropping to valley bottom.Sunday-Monday: Unstable air in the wake of the front will give ongoing cool temps, cloudy skies and flurries. Accumulations of up to 10cm are forecast.
Snowpack Summary
Thursdays heavy snowfall and strong SW winds built storm slabs up to 40cm deep over the early March rain crust (present on all aspects into the lower alpine), these remained sensitive to human triggering Friday. The mid and lower snowpack is generally well consolidated, and is made up of a series of crusts at lower elevations and on solar aspects.
Avalanche Summary
Numerous naturally triggered small to large storm slab avalanches occurred on N-E (lee) aspects during Thursdays storm. Ski cutting in a steep lee at treeline produced a small (size 1.5) storm slab avalanche on Friday, this was observed to have run on the early March crust.
Confidence
Forecast snowfall amounts are uncertain
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.