Wind has developed slabs around ridges and in lee features at upper elevations. If the sun comes out and temperatures rise, the likelihood of loose wet avalanches will increase as the snowpack warms.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
TUESDAY NIGHT - Cloudy with scattered flurries, trace to 5 cm / northwest winds, 10-20 km/h / alpine low temperature -3 C / freezing level below 1500 mWEDNESDAY - Cloudy with sunny periods and isolated flurries, up to 5 cm / west wind, 10-25 km/h / alpine high temperature -1 C / freezing level 1900 m THURSDAY - Cloudy with sunny periods and scattered flurries, 5-10 cm / northwest wind 10-25 km/h / alpine high temperature -4 C / freezing level 1700 mFRIDAY - Mix of sun and cloud / north wind 10-20 km/h / alpine high temperature -1 / freezing level 2000 m
Avalanche Summary
On Saturday, there were a few reports of natural and human triggered wind slab avalanches, mainly in the alpine on north and east facing slopes.On Sunday, small (size 1-1.5) wind slabs were reactive to skiers, generally around ridge crests and steep, convex terrain above 2200 m. The most reactive deposits were in immediate lee features, including a size 2 wind slab avalanche remotely triggered from a rocky saddle 10 m away. Overnight Sunday, a natural avalanche cycle to size 2 occurred on the western side of the Purcell Forecast region. Storm slab avalanches were observed on steep alpine slopes on all aspects.
Snowpack Summary
Recent storm snow sits on a melt-freeze crust on all aspects except for north slopes above 2000 m, snow remains dry. Southwest winds developed wind slabs around ridges and exposed treeline features and into the alpine. Below 1200 m, snow is disappearing rapidly.The base of the snowpack is composed of sugary faceted snow. The likelihood of triggering an avalanche on this layer is lower during colder periods and elevated during intense warming.
Problems
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.
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.