Weather Forecast
A very benign weather pattern will bring little precipitation, convective cloud, light winds and sunny periods over the next few days. Saturday: Scattered convective cloud cover, accompanied by light precipitation before lunch. Ridgetop winds light from the W-NW. Alpine temperatures near zero. Freezing levels 1800m falling to valley bottom at night. Sunday/Monday: A dominating ridge with diurnal temperature swings, freezing levels rising to 2000 m, and light ridgetop winds continue. Monday the ridge will start to break down and bands of cloud cover may exist later in the day.
Avalanche Summary
On Thursday reports from the region indicated many natural loose, and loose slab avalanches up to size 2 that are either wind slabs or moist loose slides due to solar warming. In the North Westerly areas of the region, an operator reported a couple skier remote slab avalanches up to size 2. These occurred on E-S aspects, above 2000 m, on the March 27th layer. Previous reports from last weekend or early in the week include remotely triggered size 3 and a natural avalanche with a 2 km wide crown was reported on an east facing aspect which started in the storm snow and then stepped down to the March 27th crust/facet combo. These shouldn't be forgotten yet; especially this weekend.
Snowpack Summary
Recent snow accumulations range from 20-40 cm over the past few days. 40-80 cm of snow from the past week is sitting on a reactive weak layer over a crust. This weak layer was buried March 27th in the Interior. We've received recent reports from the field of large, destructive avalanches occurring on this layer. Remote triggering (from afar) has also been reported. This indicates the likelihood and potential sensitivity of this layer. Slopes below 1000 m continue to experience little or no overnight refreeze (recovery). The deeper early February surface hoar layers seem to have been unreactive in the short term but still remain a concern with very heavy triggers such as a cornice fall, or step down avalanches.
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.
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.