Forecast rain, snow and fluctuating freezing levels are the name of the game. Heads up as the avalanche danger increases with this new load.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Wednesday
Weather Forecast
Wednesday: Cloudy with precipitation amounts up to 10 mm. Freezing levels up to 2200 m. Ridgetop wind light with strong gusts from the southwest. Thursday: 5-10 mm expected. Ridgetop winds light with strong gusts from the southwest. Freezing levels near 1700 m and treeline temperatures near 2 degrees. Friday: A mix of sun and cloud with isolated flurries. Freezing levels near 700 m and treeline temperatures falling to -2. Ridgetop winds light-moderate from the northeast.
Avalanche Summary
No new avalanches were reported on Monday. Forecast precipitation amounts vary, but new storm slabs and loose dry avalanches may occur at upper elevations. Loose wet avalanches are likely at lower elevations.
Snowpack Summary
A mix of rain and snow will fall on a variety of old snow surfaces including crusts and moist snow at lower elevations. In high alpine areas like Sky Pilot and the Chehalis Range the more recent (saturated) snow has refrozen into a solid crust which means that the forecast snow will likely have a poor bond to the crust. At lower elevations rain amounts will saturate the snow surfaces further.The mid and lower snowpack are well consolidated with no significant layers of concern.
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.
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.
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.