Confidence
Fair - Due to limited field observations
Weather Forecast
Monday: Expect a mix of sun and cloud, with alpine temperatures reaching -6 and freezing levels climbing to 1300m. Winds should be light to moderate from the northeast. Intense convective snowshowers are possible in the afternoon.Tuesday: Mixed skies again with alpine temperatures of -5 and freezing levels around 1400m. Winds remain light to moderate from the northeast.Wednesday: Expect clouds to build through the day with alpine temperatures reaching -4 and winds turning southwesterly.
Avalanche Summary
Both rider and remote triggered events have been reported in high (2400-2700m) north and northeast facing slopes up to size 2.0, all associated with preserved surface hoar.
Snowpack Summary
Convective snowshowers have given up to 45cm of new snow at higher elevations accompanied by light to locally moderate south/southwest winds creating new windslabs in lee locations at treeline and in the alpine. The interface of the new snow is predominantly crusts (sun, wind, meltfreeze) and the bonds are poor in some locations.The previous storm (Wednesday) was accompanied by moderate to strong south/southwest winds which left variable snow distribution in exposed areas near ridgetop with dense wind slabs in lee and cross-loaded features. These slabs are now buried, but may still be reactive to heavy triggers or in specific locations. Up to 75cm below the surface you will likely find a melt-freeze crust from previous sunny weather. At the same interface, spotty surface hoar is still being reported (up to 20mm!) in some high, north facing slopes. Where the surface hoar is present, consistent sudden results have been observed.Cornices are huge and have grown new tabs under the current conditions.
Problems
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.
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 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.