The drought has ended! Time to change our mindset and make more conservative terrain choices.
Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
Wednesday night and Thursday: Precipitation tapering off overnight as the system moves across the region. Winds should pick up in the evening to moderate speeds from the SW-W. Temperatures lowering to around -8 C in the alpine and freezing levels at the surface. Friday: Another system is approaching which should leave some light precipitation during the day (more over the W slopes of the Columbias) with strong W winds that should ease in the afternoon. Similar temperatures are expected. Saturday: More light precipitation, cool temperatures and lighter winds from the W.
Avalanche Summary
No recent avalanche activity was reported.
Snowpack Summary
Storm snow falling with strong SW-W winds in the alpine will create new wind slabs in the alpine and at treeline on lee slopes and a loose snow concern in sheltered areas. The new snow will be sitting on a variety of surfaces; sun crust on S facing slopes, surface hoar layer mostly found in shaded-sheltered areas below treeline, facets and old windslabs that were breaking down. We suspect the bond between the new snow and the old surfaces will not be very good and that it could also put on the needed load to awake the deeper instabilities that have been unreactive to skier traffic lately. The early January surface hoar layer found under the top 50-70 cm, which has been unreactive to skier traffic but still producing sudden planar shears especially under the elevation of 1500 m. in sheltered areas, could become more reactive with this added load. Under these concerning layers, a strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive.
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.