Expect variable conditions as you transition from warm temperatures below tree line to new wind affected snow in the alpine. If freezing levels rise rapidly or it rains, expect avalanche hazard to rise
Weather Forecast
Today will be a mainly cloudy day and ridge wind will be light from the SE. It was cool overnight with temps down to -5, but freezing level is forecast to reach 1800m today. A low pressure system over Oregon will spread light precip into our area this afternoon and overnight.
Snowpack Summary
20-40 cm of storm snow sits on top of a strong temperature or sun crust. At higher elevations where sheltered from sun and wind, the storm snow buries surface hoar. Mod to strong south winds have formed windslabs at ridgetop. At lower elevations, rain has soaked the upper snowpack and now below freezing temps have frozen a crust on the surface.
Avalanche Summary
Warm temperatures, precipitation and strong winds contributed to an ongoing widespread natural moist/wet avalanche cycle in the last 48hrs, especially at lower elevations. Avalanches were generally in the size 2-2.5 range, however there were some avalanches running up to size 3 in the highway corridor off of Mt MacDonald.
Confidence
Freezing levels are uncertain
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.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.