Up to 30cm of snow on Thursday with warming temperatures and strong Southwest winds. Expect natural avalanche activity to increase in size and frequency throughout the day and to continue into the weekend.
Weather Forecast
Snow arrives Thursday morning and forecasted to be 25-30cm by Thursday night! Temps will rise with the incoming snow with an Alpine high of -5 with the winds also increasing, Strong from the SW. Snow tappers off by Friday morning with temps dropping back to - 12 with moderate SW winds.
Snowpack Summary
Moderate to strong SW winds are building windslab at treeline and above. A buried surface hoar and facet interface is down 10-15 cm which will be one of the layers of concern with the incoming storm. The mid-pack is facetted and weak, with depth hoar at its base.
Avalanche Summary
A highway patrol revealed a 48-72hr old natural avalanche cycle up to Sz 3. Most occurring below ridgeline, cross loaded gullies or within steep rocky terrain on NE to W aspects in the Alpine.
Confidence
Intensity of incoming weather systems is uncertain on Thursday
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.