Regions
Northwest Inland.
Forecast new snow and wind Wednesday night are expected to create fresh wind slabs reactive to human triggers.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
TONIGHT: 5-10 cm new snow. Light southwesterly ridgetop winds. Freezing level around 500 m.THURSDAY: Mix of sun and cloud with isolated flurries. Light southwesterly ridgetop winds. Freezing level around 1000 m.FRIDAY: Mostly cloudy with flurries. Strong southerly ridgetop winds. Freezing level around 1000 m.SATURDAY: Mostly cloudy with flurries. Moderate southwesterly ridgetop winds. Freezing level around 1200 m.
Avalanche Summary
Numerous natural loose wet avalanches up to size 2 were reported on Tuesday.
Snowpack Summary
Rising freezing levels and daytime warming have created moist or wet snow surfaces on all but alpine, northerly aspects where 20 cm up to 50 cm of recent storm snow has been redistributed by strong winds. Weak layers buried around March 19th are roughly 40 cm below the surface (up to 100 cm in deeper snowpack areas). These weak layers include surface hoar on shaded aspects at high elevations and hard crust layers on solar aspects and below treeline.Near the bottom of the snowpack, weak and sugary facets are found in shallow, rocky snowpack areas. Storm slabs have stepped down to these facets and producing very large avalanches in northern parts of the region.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.