Diligence may be required to maintain conservative decisions in the face of fair weather and decent riding conditions over the weekend.
Weather Forecast
Mostly cloudy with a chance of light flurries Friday evening and Saturday, but generally dry for Sunday. Freezing levels remain in valley bottoms for the forecast period, with above freezing alpine temperatures expected for Friday. Winds should remain generally light and variable.
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
Warm temperatures are aiding in the settlement of the recent storm snow resulting in sensitive 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 80-120 cm down in the snowpack the mid-December surface hoar/crust weakness continues to be highly sensitive to human triggers with reports of remote triggering and long fracture propagations.
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.