Shifting winds have formed wind slabs on a variety of aspects. At this time of year the sun can have a surprisingly powerful effect on the snow. Strong solar radiation can weaken cornices and initiate point releases in powdery snow especially on steep rocky south facing slopes.
Wind direction has shifted from southwest during the storm through northwest, to northeast Monday. The freshest wind slabs may be found on atypical aspects and features.
Cornices overhead are a primary concern during sunny, warm, or windy conditions. Cornice failures are dangerous on their own, but they also have potential to trigger large persistent slab avalanches that would otherwise be difficult to trigger.
Sunday night: Clearing, light northwest wind, low of -20.
Monday: Sunny, moderate northeast wind, high of -14.
Tuesday: Increasing cloud in the afternoon, light to moderate northeast wind switching northwest, high of -12.
Wednesday: A mix of sun and cloud, moderate northwest, high of -8.
A natural size 2 wind slab was observed on a northeast aspect in the alpine during the strong wind event on Saturday. Previous natural activity observed on Thursday was limited to size 1-1.5.
Several skier triggered wind slabs size 1-1.5 have been reported over the past few days, most in predictably wind loaded lees or convexities, near ridgetop, around treeline or higher.
10-20 cm of recent snow has been extensively wind affected at upper elevations, with exposed windward features scoured down to the crust. Below 1300 m, a surface crust has formed over moist snow.
The recent snow sits over a 10-20 cm thick rain crust which effectively caps the underlying snowpack, making human triggering of avalanches on weak layers deeper in the snowpack very unlikely. Large cornice failures may still have potential to trigger these deeper layers.
