A Special Public Avalanche Warning continues for this region. Conservative route selection and cautious decision-making is required.
Weather Forecast
Sunday: Cloudy with sunny breaks and a chance of flurries. The freezing level is around 600-1000 m and winds are light from the S-SW. Monday: Cloudy with sunny breaks. The freezing level remains near 600-1000 m and winds are light from the S-SW. Tuesday: Cloudy with light to moderate snow. The freezing level rises to 1500 m and winds increase to moderate from the S-SW.
Avalanche Summary
Widespread natural slab and loose wet avalanches up to size 3 were reported throughout the region on Friday. Large slabs were observed on all aspects at all elevations (despite limited alpine observations due to poor visibility). There were also a report of a size 2 accidently skier-triggered slab that sympathetically released several other slabs up to size 2.5 on nearby slopes. Natural activity should slow down with cooler and drier weather this weekend; however, human triggering remains a concern in many areas (especially slopes between 1500 and 1800 m that didn't release naturally during the storm - even low angle slopes).
Snowpack Summary
This weeks "Pineapple Express Light" brought an average of 60 cm of new snow to the region. The snow line may have gone up to ridge top in the south, but only 1400-1600 m in the north. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading from snow and rain, and the resulting avalanche cycle, has helped flush-out the mid- and early-January surface hoar/facet layers now down 80-120 cm deep. However, these layers are likely still intact and reactive in places and it may still be possible to trigger large slabs. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.
Problems
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.
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.