Avalanche hazard will steadily rise as snow load increases over newly buried surface hoar and crust layers.
Weather Forecast
Low pressure system will arrive to the Interior this morning bringing light to moderate amounts of snow with rising freezing levels to ~1000m. Treeline winds are forecast to stay light for most of the day and will pick up tonight. This unsettled pattern will continue for the next few days with a series of fronts that will pass through our region.
Snowpack Summary
Up to 20 cm of snow overlies the Jan 30 crust which can be found up to 2200m. Surface hoar was found on the crust and facetting has been occurring underneath it. Above 2200m firm wind pressed snow is found 20cm down. The Jan 15 surface hoar layer is down 60-90cm. The Dec 17 surface hoar/ crust complex is down 130-180cm.
Avalanche Summary
Yesterday, there was a report of a human triggered avalanche, size 1.5 at Bruins Pass into 8812 Bowl off the east ridge of 8812 Peak ~2700m, SE aspect, 15-20cm deep. Along the highway corridor there were was one loose natural avalanche size 1.5 east of the Rogers Pass summit.
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.
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.