An elevated Avalanche Danger exists on the east side of the divide where recent heavy storm loading occurred. Solar warming will drive the Avalanche Danger throughout the forecast period.
Confidence
Moderate - Due to the number of field observations on Tuesday
Weather Forecast
A well-embedded ridge of high pressure will maintain a mix of sun and cloud for the forecast period. Ridgetop winds will be generally light, while freezing levels will sit at about 2200m on Wednesday and Thursday, and then climb to about 2700m on Friday.
Avalanche Summary
At the time of publishing this bulletin on Tuesday there were some reports of smaller loose wet avalanches, although observations were very limited. The sun will become the main driver for avalanche activity throughout the forecast period. Although warming will promote settlement and strengthening within the recent storm snow, loose wet avalanches and cornice falls will become the most common avalanche type. Another concern, however, remains very isolated yet destructive releases on deeper weak layers which formed earlier in the season. Avalanches on these layers could run surprisingly long distances, and may be triggered by a cornice fall, a surface avalanche in motion or extended periods of warming.
Snowpack Summary
New snow and wind on Monday formed storm slabs which were especially deep on the east side of the divide. Reports suggest warming has promoted settlement and strengthening within the new snow. The current warming trend has also promoted a daily melt-freeze cycle on solar aspects at higher elevations, and on all aspects below treeline. About 15-60cm below the surface you'll likely find a widespread hard crust, although reports suggest a reasonable bond has developed between the crust and the overlying slab. Deeply buried weak layers near the ground are becoming hard to find, but may remain sensitive to triggering from significant warming or with large loads such as cornice fall. Large cornices overhang alpine slopes and will become increasingly weak with forecast solar radiation.
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.
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.