A Special Public Avalanche Warning is in effect for this region. Widespread, large avalanche activity is possible on touchy buried weak layers. Don't overthink it - maintain very conservative terrain choices and avoid overhead exposure.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
SATURDAY: Early morning snowfall, accumulation 1-3 cm, then mostly sunny, moderate northwesterly winds, alpine temperature near -4 C, freezing level near 1000 m.SUNDAY: Mostly sunny with possible valley cloud, light to moderate northwesterly winds, alpine temperature near 0 C, inversion conditions with cold valley air and above-freezing level between about 2000 m and 2500 m.MONDAY: Mostly sunny, light southwesterly winds, alpine temperature near 0 C, freezing level near 2500 m.
Avalanche Summary
The recent 40 cm of snow has been reactive and produced small to large slabs or loose dry avalanches. One release stepped down to the early-season rain crust and facet layer. Storm slabs have most often been observed in direct lee features and steep slopes. Around 1900 m, ongoing reports of touchy conditions have been noted, such as whumpfing and cracking, which is indicative of touchy buried weak layers.
Snowpack Summary
An unstable weak layer from mid-December (predominantly feathery surface hoar crystals and/or a sun crust) is found at treeline and below treeline elevations. Slabs can fail easily on this layer, either naturally or with the weight of a person or machine. Forecasted warm air temperatures could increase slab properties of the overlying snow and make this layer easier to trigger.The snowpack is variable across the region, but persistent slabs are generally a widespread problem. Wind slab and storm slab distribution will be more variable. New wind slabs can be found in parts of the region due to recent southwest winds. Windward alpine slopes may be scoured; and variable wind slabs are found at treeline and alpine elevations. New snow is likely to fail as storm slabs and/or loose avalanches. Deeper in the snowpack, an early-season rain crust and sugary facets exist. An avalanche in motion could step down to these deeper layers, creating a large and destructive avalanche. Overall snowpack depths are variable across the region. It is generally shallower in the east.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.