Watch for a wide range of conditions (and avalanche problems) as winter and spring weather patterns collide.
Confidence
High - Timing or intensity of solar radiation is uncertain on Wednesday
Weather Forecast
On Wednesday, expect overcast skies and light flurries in the morning with clearing skies in the afternoon. The developing ridge of high pressure will ensure clear skies for Thursday and Friday as well. Ridgetop winds will be strong from the southwest on Wednesday morning, and then drop to light for the rest of the forecast period. Freezing levels will rise from 1500m to 3000m throughout the day on Wednesday. On Thursday and Friday, the freezing level will hover between 3200m and 3700m.
Avalanche Summary
Although observations from the last few days were extremely limited, fresh wind slabs to size 1 were reported to have been triggered under light loads in high elevation terrain. With forecast warming and solar radiation, we'll see a transition to more spring-like avalanche problems. Loose wet avalanches, and large cornice falls are expected to occur throughout the forecast period
Snowpack Summary
Between 10-30cm of recent snowfall overlies a mix of hard crusts on high elevation solar aspects, settled dry snow in north-facing alpine terrain, and moist snow everywhere else. The recent snow has been shifted by strong southerly winds into fresh wind slabs in wind-exposed terrain. With forecast solar radiation and warm temperatures, most surfaces will transition to a daily melt-freeze cycle, while recently formed wind slabs will linger on high north-facing slopes. Below the new snow, the snowpack is generally strong and well-settled. Cornices are huge and will become weak with future warming and solar radiation.
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.
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.