Carefully assess the top 50cm of the snowpack for cohesion and slab development. Storm slabs will be easily triggered and may propagate into large avalanches.
Weather Forecast
A frontal system will track into the area this morning with moderate SW winds. Light precipitation is expected with up to 10cm of accumulation by late Sunday afternoon. Freezing levels will remain below 1300m.
Snowpack Summary
In the alpine up to 40cm of new snow buries the January 4th interface. This interface is surface hoar in protected areas, sun crust on steep S - SW aspects and loose facets at tree-line and below. Where wind-affected, storm slabs have formed in lee features. At lower elevations, the mild temp's and snow settlement are creating storm slabs.
Avalanche Summary
Three size 2 avalanches were observed in the highway corridor east of Rogers Pass. The avalanches were triggered in the developing storm slab layer.
Confidence
Intensity of incoming weather systems is uncertain
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.