Regions
Northwest Inland.
No significant snowfall is expected in the next few days, but be aware of the potential for triggering wind slabs in exposed terrain.
Confidence
Good - Due to the number of field observations
Weather Forecast
Cool temperatures and flurries in the forecast for the next few days. No significant snowfall or change in the weather for the the next week.
Avalanche Summary
One operator in the north of the region has reported several natural wind-slab avalanches, up to size 2.5, in steep west facing terrain in the alpine. No other reports of avalanche activity.
Snowpack Summary
A thin melt-freeze crust now covers the 40-80 cm of recent storm snow up to at least treeline. Strong and variable winds have created soft and stiff wind slabs on varying aspects in exposed terrain. Below the recent storm snow is a rain crust at lower elevations and a temperature crust has formed in some locations from the recent temperature inversion. In the mid-pack a surface hoar layer has been reported, although it appears to be spotty in distribution. Near the bottom of the snowpack is a crust facet combo that was buried in mid-November.
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.