Newly formed wind slabs may remain touchy on Friday. Cornices are also large and weak.
Confidence
High - Due to the number of field observations on Thursday
Weather Forecast
Light flurries are expected on Friday, although a brief pulse will bring 5-10cm of snow to region on Friday night. Expect a mix of sun and cloud on Saturday with generally clear skies on Sunday. Ridgetop winds will be strong from the west with Friday night's system and then become mainly light for the weekend. Daytime freezing levels should hover between 1300m and 1500m for the forecast period.
Avalanche Summary
Avalanche observations on Thursday were limited due to stormy weather, although I'm sure there was some natural wind slab activity in high elevation lee terrain in response to new snow and wind. Looking forward to Friday, natural activity may taper-off; however, newly formed wind slabs may remain sensitive to human triggering.
Snowpack Summary
Up to 10mm of precipitation fell on Thursday. At treeline and in the alpine, precipitation fell as snow and strong southwest winds have likely formed fresh and reactive wind slabs. I'm sure cornices are huge and weak. Rain below about 1650m has left surfaces moist or saturated. About 20-40cm below the surface you may find a melt freeze crust which formed during the 2nd week of February. At the same interface, you may find surface hoar which most likely exists on high, north facing terrain. Rain and warm temperatures have likely flushed out this weakness in most areas; however, continued reactivity may exist in high elevation terrain above the recent rain line. West of the divide, a layer of buried surface hoar can be found between 50 and 70cm below the surface. Recent reports suggest this layer has become less of a concern.
Problems
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.