Wind is driving the avalanche danger on Monday. I would expect to find touchy wind slabs on lee features below ridgetops and good skiing in sheltered terrain.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
MONDAY: 10-20 cm of new snow is expected by Monday afternoon, moderate southwesterly ridgetop winds, and temperatures around -18. TUESDAY: Mostly sunny with cloudy periods, moderate northwesterly ridgetop winds, and temperatures around -20. WEDNESDAY: Mostly sunny with cloudy periods, moderate northerly ridgetop winds, and temperatures around -20.
Avalanche Summary
On Saturday, a size 1 skier triggered wind slab was reported on a southwest aspect. I expect human triggered wind slab activity to increase on Monday with the forecast new snow and wind.
Snowpack Summary
Forecast 10-20 cm of new snow by Monday afternoon and moderate southwest winds are expected to create fresh wind slabs on lee features at treeline and above. Recent snow has also covered old, thicker wind and hard slabs from previous wind events. Persistent and deep persistent weakness in the mid and lower snowpack are giving variable results in snowpack tests, but are generally most touchy in shallow snowpack areas. Recent snowpack tests gave moderate but resistant results on facets and/or surface hoar buried mid-December where it was found down 45 cm, and hard but sudden collapse results on the facet/crust weakness down 116 cm near the base of the snowpack.
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.