Avalanche Danger at Treeline may be subject to an increase depending upon just how severe the chinook winds forecast over the next 48 hours become. Watch out for daytime heating influences that will affect both ski quality and safe travel.
Weather Forecast
Little to no new snow expected over the weekend. Winds will pick up in intensity and we will see more redistribution of last Sundays's storm snow occurring. Temperatures have already begun a steady rise and we are seeing solar influences at treeline and below. A strong upper ridge of high pressure will keep skies mainly clear with temps above normal values.
Avalanche Summary
Widespread sluffing of loose dry storm snow is the most common avalanche observation again Friday. In a few areas the sluffs are entraining enough volume to be considered Size 2's. No new slab avalanche activity was observed.
Snowpack Summary
Below treeline surface layers in solar exposed areas are becoming moist with daytime heating and a thin crust has formed. Steep southerly aspects at higher elevations are also suffering from some solar exposure as well. Fracture characteristics exhibited in a hasty profile on a 30 degree north facing aspect at treeline showed a 'progressive compression' in a 30cm storm snow layer. The storm snow layers appear to be bonding well to the old surface layers. Larger and more fragile cornices are likely to form.
Problems
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.