Diligence may be required to maintain conservative decisions when seeking decent riding conditions over the weekend.
Weather Forecast
Only trace amounts of snow are expected throughout the forecast period. Overcast conditions are forecast for Sunday, although skies should become increasingly clear on Monday and Tuesday as a dry ridge of high pressure becomes the dominant air mass. Ridgetop winds should remain generally light, while freezing levels will remain at valley bottom.
Avalanche Summary
Natural avalanche activity has tapered off, but storm and persistent slabs remain highly sensitive with several reports of human-triggered avalanches up to Size 2 and explosive-triggered avalanches up to Size 3. Of note were several remotely triggered avalanches involving persistent slabs showing the ability of these weaknesses to propagate into very large avalanches.
Snowpack Summary
Recent warm temperatures have aided in the settlement of the recent storm snow resulting in storm slabs up to 70 cm thick. A breakable surface melt-freeze crust can be expected on all aspects below approximately 1800 m and sun-exposed slopes above. Around 80-140 cm down in the snowpack the mid-December surface hoar/crust weakness continues to be sensitive to human triggers with reports of remote triggering and long fracture propagations.
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.