Regions
Northwest Inland.
Confidence
Fair - Due to limited field observations
Weather Forecast
Wednesday: Light snowfall with periods of sun mixed in - 5-10cm. The freezing level should rise to around 1000m during the day. Winds are moderate from the south, shifting to light from the north. Thursday and Friday: A ridge of high pressure builds in bringing mainly sunny skies and light winds. The freezing level should bounce from near valley bottom overnight to 700-1000m during the day.
Avalanche Summary
No new avalanches have been reported but there are few observers in the field. It's likely that thin wind slabs are the primary issue up high, with solar related activity on sunny slopes during the day.
Snowpack Summary
Light amounts of new snow overlie a variety of old surfaces. These surfaces include crusts (found on all aspects below 1000m and on solar aspects higher up), and old wind slabs. Below this the snowpack is mostly well settled and strong; however, the mid-February surface hoar (buried 80-120cm deep) may still react to large triggers in isolated terrain. Cornices in the area are reported to be very large and potentially unstable.
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.
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.