Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Ridging will bring mostly clear conditions to the region on Sunday with light westerly winds and freezing levels at about 1700m. Light precipitation will commence late Monday intensifying slightly overnight and into Tuesday. Winds will be moderate/westerly, switching light/northwesterly by Tuesday. Freezing levels are expected to increase to 1900m on Monday dropping back to 1700m by Tuesday. Confidence: Good for Sunday, fair for Monday/Tuesday.
Avalanche Summary
Numerous wet slab and wet loose snow avalanches to size 2.5 were reported in the region on Friday. They failed on various aspects at lower elevations, and occurred in response to daytime warming.I suspect cooling on Saturday will assist in limiting avalanche activity at higher elevations; however, it's all about solar radiation and freezing levels at this time. If it warms-up and/or if solar radiation intensifies, avalanche activity will increase.
Snowpack Summary
Very warm temperatures dominated the region throughout the week and all but the highest, north-facing slopes saw moist to wet surface conditions. Since Thursday morning, slightly cooler temperatures have allowed light amounts of new snow to fall above about 2000m while rain continued to penetrate and weaken the snowpack at lower elevations. Up to 80cm below the surface, you might find remnants of facetted crystals sitting on a crust in the alpine and at treeline. The mid-February buried surface hoar layer is down about 140-220 cm, although avalanches releasing on this layer represent a very low probability-high consequence scenario. Cornices in the region are very large. With spring temperatures, these are more likely to become weak and fail. They could provide a large enough trigger to release deep layers on slopes below.
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.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
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.