Avalanche danger will vary from place to place depending on local snowfall amounts and freezing levels. The heaviest precipitation is expected in the west.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
Tuesday night/ Wednesday: 10-30 cm snow. Strong to extreme W winds. Freezing level around 1500 m overnight, rising to near 2000 m in the south (~1700 m in the north). Thursday: Light snow. Moderate to strong NW winds. Freezing level around 1600 m. Friday: Light snow. Light S winds. Freezing level around 1500 m.
Avalanche Summary
An avalanche cycle of slabs up to size 3 occurred during last weekend’s storm. Many of these events were on NE-NW aspects above about 2400 m. Several size 2 skier-remote triggered slabs were also reported on Sunday. These failed on surface hoar buried below the storm snow. They occurred on W-NE aspects above 2500 m. Little activity was reported on Monday.
Snowpack Summary
Up to 50 cm recent storm snow is sitting on a variable interface, consisting of a crust, moist snow, surface hoar or facets. The surface hoar or facet interface is mainly found on high-elevation northerly aspects. It has recently been very touchy, with remote skier-triggering occurring. Forecast precipitation will add to this storm slab problem and create new wind slabs at high elevations, and weaken the snowpack with rain at low elevations. Large cornices are likely to increase in size and become more prone to failure during Wednesday’s storm.
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 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.