Keep an eye on the sun and rising temperatures: the chance of loose wet avalanches will increase as the snowpack warms.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
WEDNESDAY NIGHT - Cloudy with clear periods and isolated flurries, up to 5 cm / west wind, 10-15 km/h / alpine low temperature -6 C / freezing level 1000 m THURSDAY - Cloudy with sunny periods and isolated flurries, trace to 5 cm / southwest wind, 10-15 km/h / alpine high temperature -4 C / freezing level 1900 mFRIDAY - Cloudy with scattered flurries, 5-10 cm / north wind, 10-25 km/h / alpine high temperature -3 C / freezing level 1800 mSATURDAY - Cloudy with scattered flurries, trace to 5 cm / southwest winds, 15-35 km/h / alpine high temperature -1C / freezing level 1900 m
Avalanche Summary
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 and into Monday, a natural avalanche cycle to size 2 occurred on the western side of the Purcells Forecast region. Storm slab avalanches to size 2, with crowns 20-50 cm deep were observed in alpine terrain on all aspects. On Tuesday, skiers were able to trigger slabs up to size 1.5 in steep, gully features as low as 2200m. Explosives produced avalanches to size 2 and a helicopter remotely triggered a size 1.5 avalanche from 200 m away, these avalanches all started in steep, alpine terrain above 2400 m, mostly on northerly aspects.
Snowpack Summary
Recent storm snow sits on a melt-freeze crust on all aspects except for north slopes above 2100 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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.