Regions
Northwest Inland.
New snow may be hiding hard old wind slabs. Watch out for lee features even if there aren't obvious signs of fresh wind loading.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
MONDAY: flurries overnight clearing to become mainly sunny, light to moderate westerly winds, 1000m freezing level. TUESDAY: partly cloudy, moderate westerly winds, 1200m freezing level. WEDNESDAY: mainly sunny, light southerly winds, 1200m freezing level.
Avalanche Summary
No new avalanches were reported over the weekend.
Snowpack Summary
Moderate winds have created fresh wind slabs in the alpine and at treeline, and grown cornices at ridgeline. The recent snow may sit above a crust on sunny aspects or surface hoar in isolated shady locations. A more widespread crust may be found just below the surface at lower elevations. In general the upper snow pack is reported to be bonding well to a crust buried in early February, now 40 to 80cm down, that extends up to around 2000m. The early January surface hoar can typically be found between 60 and 140cm down. Although it is getting harder to trigger in most places this layer remains a concern, especially in the north and east of the region. Shallow snowpack areas also have a weak base layer of facetted snow just above the ground.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.