The winds will likely drive the avalanche danger over the next day or so. If you see loose snow drifting or getting blown off ridgecrests, expect an increase in wind slab activity.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Saturday: Mix of sun and cloud with light snowfall expected on Saturday night / Moderate westerly winds / Alpine temperatures of -13Sunday: Mix of sun and cloud with light flurries / Moderate northeast winds / Alpine temperatures of -18Monday: Mix of sun and cloud / Strong northeast winds / Alpine temperatures of -20
Avalanche Summary
A large human-triggered avalanche was reported from Corbin yesterday on a wind affected slope in an area where weak facets were present. While technically this area is in the Lizard/Flathead area, I feel as though it is indicative of conditions in the South Rockies region. Where you get a combination of weak sugary snow lower in the snowpack and a supportive upper slab, conditions are ripe for avalanches to be human-triggered at this time. There's lots of loose snow available for redistribution, so if the wind picks up, expect an increase in wind slab avalanche activity.
Snowpack Summary
Up to 20 cm of fresh low density snow has been redistributed by mainly southwesterly winds forming wind slabs in the lee of ridgetops. In general, there is very little structure to the snowpack, with low density new snow sitting over soft, sugary facets. Travel is very challenging as a result. A variable interface that formed during the cold snap in early December can be found buried 30-50 cm deep. This interface consists of weak faceted (sugary) snow and preserved surface hoar in sheltered areas. The interface is likely most reactive in wind-affected terrain where it is covered by hard wind slabs. The snowpack is a generally weak and faceted below this interface, including another weak layer with surface hoar or facets that was buried in early December. Hazards such as stumps, rocks, and open creeks are still a major concern.
Problems
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.
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.