Regions
Northwest Inland.
Watch for thin wind slabs in the alpine that could be problematic, especially in complex terrain.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday
Weather Forecast
Wednesday: Increasing cloud cover. Light SW winds at treeline, Moderate NW winds at ridgetop. Freezing level rising to 800m, lowering to valley bottom overnight. No significant precipitation. Wednesday Night: 1 to 2cm of snow. Thursday: 2 to 5cm of snow. Moderate SW winds at treeline, Strong to Extreme SW winds at ridgetop. Freezing level rising to 800m, holding there through Thursday night. Friday: No significant precipitation. Light SW winds at treeline, Strong W/SW winds at ridgetop. Freezing level holding at approx. 1000m.
Avalanche Summary
Over the weekend avalanches to size 3 were reported from steep un-skiable south through west facing terrain features and isolated cornice fall produced a few slabs out of extreme terrain. Very thin wind slabs on NE facing alpine features were also observed. Glide cracks are starting to open up too.
Snowpack Summary
Northerly winds have likely created isolated stiff thin wind slabs in lee alpine terrain. A variety of other surfaces can be found including a skiff of recent snow, a sun crust, an old rain crust, surface hoar, and/or surface facets. At the base of the snowpack, weak facets may be found. Keep an eye out for cornices that could become weak with daytime warming.
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.