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: Snow beginning Sunday evening and is expected to accumulate to 15-20 cm by Monday afternoon. Moderate southwesterly ridgetop winds, and temperatures around -10.TUESDAY: Mix of sun and cloud, moderate northwesterly ridgetop winds, and temperatures around -15.WEDNESDAY: Mostly sunny with cloudy periods, light northwesterly ridgetop winds, and temperatures around -15.
Avalanche Summary
On Saturday, one natural and several human triggered size 1 wind slabs were reported on a variety of aspects. 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. The mid-December facet/surface hoar persistent weakness can be found buried 70-120 cm deep and is generally giving hard resistant or no results in snowpack tests. However, we are still receiving occasional reports of sudden results, suggesting that it has to potential to propagate into a large avalanche if triggered, particularly in shallow spots where this layer closer to the snow surface. The lower snowpack is well bonded and features a thick rain crust near 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.