*** UPDATE*** Heavy loading from snow and wind is likely resulting in large natural avalanches. Travel in avalanche terrain is not recommended without professional-level safety systems.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
FRIDAY: Cloudy with flurries bringing another 5-10 cm of fresh snow, moderate to strong southwesterly winds, and freezing level remaining at valley bottoms.SATURDAY: Cloudy with light flurries 2-5 cm of fresh snow, moderate to strong westerly winds, and freezing levels around 1300 m.SUNDAY: A mix of sun and cloud with moderate southwesterly winds and freezing levels as high as 1500 m.
Avalanche Summary
Reports of natural and skier-controlled wind and storm slab avalanches up to Size 1.5 continues. Storm slabs are expected to remain sensitive to light triggers, especially where winds have promoted slab formation and heavy loading from snow and wind could result in continued natural avalanche activity.
Snowpack Summary
10-20cm of fresh snow, accompanied by moderate winds, adds to the 25-40 cm from the past few days, with the highest amounts in the southern part of the region. This recent storm snow has settled into a slab, especially where it has been wind-loaded or warmed by the sun, which is bonding poorly to the previous snow surface that includes sun crust on steep sun-exposed slopes, faceted snow, as well as surface hoar on sheltered open slopes. Recent reports identify buried sun crust as a particular problem. Weaknesses are also lingering within the recent storm snow, with several easy to moderate shears being reported in areas with higher amounts of recent storm snow. A persistent weakness buried mid January is now down 50-80 cm and consists of buried surface hoar in sheltered areas, and/or widespread faceted old snow. It has generally stabilized but may be sensitive to triggering in isolated areas where buried surface hoar is preserved. Another surface hoar/facet persistent weakness that was buried mid-December can now be found down roughly 110-130 cm. While activity at this layer has declined, professionals in the north of the region are still treating it with caution.
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.