A nice surprise today, up to 10cm of new snow has buried the Dec crust. The new snow will take a day or two to settle. In the meantime, asses the conditions throughout the day.
Confidence
Fair - Wind speed and direction is uncertain
Weather Forecast
A bit of an unusual temperature pattern for tomorrow. Lower elevation temps will rise while the upper elevations remain steady. A brief inversion is expected tomorrow morning. 2500m winds will be light to moderate, with upper winds into the strong range. The snow has ended, and it will stay that way for a few days.
Avalanche Summary
Nothing new was seen today.
Snowpack Summary
We had almost 10cm's of new snow at valley bottom. This was slightly more than forecasted. The snow today had an "upside down" feel to it. The surface snow was slightly more dense than the layer below. The Dec 18th rain crust is going strong in the Commonwealth valley. It is still very apparent, yet it is supportive in most areas with the new snow. The snow immediately above(a very thin layer) and below is faceted. The midpack has continued to degrade in quality. The layers at the bottom, the Nov 6th crust, is extremely weak. Despite the conditions, there was no whumphing noted. There was some mild cracking on convex rolls and unsupported terrain. Upper treeline and alpine observations were limited today.
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.
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.