Regions
Northwest Inland.
New snow fell in the south of the region. Expect to find loose dry snow in sheltered areas and storm slabs in exposed areas. New and old slabs aren't bonding well to underlying layers. Conservative decision-making is recommended.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
THURSDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, moderate southwesterly winds, alpine temperature -7 C, freezing level 700 m.FRIDAY: Mostly cloudy with trace snowfall, light southeasterly winds, alpine temperature -10 C, freezing level 500 m.SATURDAY: Mostly cloudy with trace snowfall, light southerly winds, alpine temperature -9 C, freezing level 600 m.SUNDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, light southwesterly winds, alpine temperature -9 C, freezing level 600 m.
Avalanche Summary
Evidence of a widespread avalanche cycle was observed on Wednesday and Thursday. Large to very large (size 3 to 4) storm slabs were observed, often in southeast, east, and northeast slopes. Some of these stepped down to weak and sugary facets at the bottom of the snowpack.
Snowpack Summary
Thursdays storm is expected to bring another 10 to 30 cm of snow to the southern parts of the region. This overlies last weekends 40 cm of storm snow, which has settled into a reactive slab and is not bonding well to old snow surfaces. These include two layers of surface hoar, which exist on shaded aspects at high elevations as well as a melt-freeze crust on all aspects at treeline and below treeline elevations.Deeper in the snowpack, layers of crusts, facets, and isolated surface hoar buried 50 to 100 cm exist from mid- and late-February and a surface hoar/crust layer from January is buried around 150 to 200 cm. Near the bottom of the snowpack, weak and sugary facets exist, particularly in steep, rocky, and shallow snowpack areas. Shallower storm slabs have stepped down to these facets recently, producing very large avalanches.
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.