Continue to use caution due to the weak layers buried in the snowpack.
Weather Forecast
WEDNESDAY NIGHT: Mostly clear skies, freezing level below valley bottom.THURSDAY: Increasing clouds over the day, light to moderate southwest winds, alpine temperature -5 C, freezing level 1000 m.FRIDAY: Mostly cloudy with light snowfall, accumulation 1 to 3 cm, light to moderate southwest winds, alpine temperature -1 C, freezing level 1800 m.SATURDAY: Mostly cloudy with light snowfall, accumulation 1 to 3 cm, light southwest winds, alpine temperature -3 C, freezing level below valley bottom.
Avalanche Summary
Evidence of a small avalanche triggered by a snowmobile was observed on Tuesday, releasing on the surface hoar layer described in the Snowpack Summary. Shooting cracks were also observed, suggesting instability with that layer. Otherwise, no new avalanches were observed.
Snowpack Summary
Around 10 to 30 cm of snow overlies a weak layer of feathery surface hoar crystals, with the most snow found at higher elevations. The surface hoar is most prominent between 1500 and 1900 m. The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.