With snow expected to begin on Friday and continue into the weekend, watch for touchy wind slabs building in alpine, lee areas.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
FRIDAY: Cloudy, flurries. Accumulation up to 5 cm. Ridge wind light to moderate from the northwest. Temperature -1. Freezing level 800 m.SATURDAY: Mix of sun and cloud, flurries. Accumulation 5 cm. Ridge wind light from the west. Temperature -3. Freezing level 800 m.SUNDAY: Cloudy, flurries. Accumulation 5-15 cm. Ridge wind moderate from the southwest. Temperature -2. Freezing level 800 m.
Avalanche Summary
There have been no reports of avalanche activity since the weekend when a small, natural, wind slab avalanche was observed in the alpine on a wind-loaded, north-facing, ridge top feature on Saturday in the Metal Dome area.
Snowpack Summary
A melt-freeze crust exists on the surface on all aspects. On north aspects this surface crust is thin with dry, sugary snow crystals (facets) below. Beneath the surface, the upper snowpack is well settled and overlies a thin layer of facets on the late-November rain crust. The most recent snowpack tests from last week have found hard, sudden compression test results on the facets just above the crust, which is now buried between approximately 60 cm at treeline elevations. Beneath this crust the lower snowpack is well settled and consists of several crusts that formed in the early season.
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.