Warm temps rapidly destabilized the snowpack yesterday, even through the clouds. More sun is expected today. Minimize your exposure to solar aspects, and to slopes with cornices overhead. Avalanches are traveling far and fast; regroup in safe spots!
Weather Forecast
The flurries should taper off this morning. We should see a mix of sun and cloud, with mild temps. As a result, we will likely see similar avalanche activity to yesterday. A weather system arriving on Friday will bring increasing cloud, westerly winds will become moderate, with up to 10cm by saturday morning. Saturday we may see some sun breaks.
Snowpack Summary
Yesterday's 20cm of new snow bonded poorly and became reactive with warm temps (see below), especially on solar aspects where it buried a sun crust. There are several crusts in the top meter which react with hard sudden results in tests. The Feb10 layer is down ~2m, shallower in thin areas, and continues to be a concern.
Avalanche Summary
Yesterday there were several reported of loose, moist avalanches triggered by skiers. They were easily triggered and entrained snow to size 2.5. They ran fast and and far, and into mature timber. Numerous natural avalanches also occurred from all aspects along highway corridor and in the backcountry. Most were size 2 but some were up to size 3.5.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
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.