Avalanche conditions are still very dangerous! It's hard to have any confidence traveling in the backcountry with such a complex snowpack and sustained warming.
Weather Forecast
TUESDAY: Increasing cloud throughout the day, moderate southwest winds, mild inversion with alpine temperatures hovering around 0 C.WEDNESDAY: Light flurries in the afternoon, strong southwest winds, alpine temperatures around - 2 C.THURSDAY: 5-10 cm of new snow, strong southwest winds, alpine temperatures around -5 C.
Avalanche Summary
On Monday, a few solar triggered avalanches (up to size 2.5) were reported in steep terrain. A small wind slab (size 1.5) was also reported on a northeast alpine feature. On the weekend, explosive testing produced several large persistent slab avalanches on deep weak layers, including a size 3.5 persistent slab that failed on the November crust. This avalanche ran nearly 800 m and exceeded the path's historic runout distance. Very significant avalanche activity occurred in the region last week, and the potential for more large avalanches remains.
Snowpack Summary
Warm alpine temperatures are rapidly settling recent storm snow as well as forming moist snow on solar aspects. More importantly, warming is stressing deeper layers in the snowpack. The early January surface hoar layer is roughly 60 cm below the surface and the unstable weak layer from mid-December (predominantly surface hoar and/or a sun crust) is found roughly 100 cm below the surface at treeline and below treeline elevations. Below, a rain crust that developed late-November with associated sugary facets is also being stressed. Snowpack test results show sudden fracture characters and high propagation potential for all of these buried layers, indicating that they can be triggered and could propagate into large, destructive avalanches.
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.