Friday's forecast calls for steady precipitation and rising freezing levels. This is a great recipe for avalanche activity.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Friday
Weather Forecast
Friday: 10-25cm of new snow on Thursday night with an additional 10-15mm of precipitation on Friday / Strong westerly winds / Freezing level at 900m, climbing to 1800m by Friday afternoonSaturday: 10mm of precipitation / Light and variable winds / Freezing level at 1400mSunday: 10-20mm of precipitation / Light southwest winds / Freezing level at 2300mNote: Confidence is low for forecast wind values and precipitation amounts for Saturday and Sunday.
Avalanche Summary
No new avalanches were reported on Thursday. New precipitation and wind on Wednesday night is expected to promote a new round of storm slab activity in high elevation lee terrain, and loose wet avalanche activity on steep, lower elevation slopes.
Snowpack Summary
As of Thursday morning, between 10 and 25cm of new snow had fallen. In areas where winds were strong, new wind slabs likely exist. At treeline and below, the new snow overlies either a crust or moist snow from Monday's rain event. In high alpine areas like Sky Pilot and the Chehalis Range the new snow overlies thick storm slabs which developed during the stormy weather at the end of January.A thick crust exists up to 180cm below the surface, although a strong bond is expected at this interface.
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.