Fresh storm slabs may bond poorly to chunky, variable crusts. If you see more than 30cm new snow on a firm crust, consider the danger to be HIGH.
Confidence
Low - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
We're looking at significant precipitation totals from Saturday evening right through all of Sunday. Unfortunately it will get warm on Sunday afternoon. SUNDAY: Snow changing to rain by noon. Accumulation 15-20 cm snow / 20mm rain. Ridge wind moderate from the southwest. High temperatures near +2. Freezing level rising to 1800 m.MONDAY: Cloudy with sunny breaks and isolated flurries. Accumulation 5-10 cm possible. Ridge wind light from the west. Temperature near 0. Freezing level 800 m.TUESDAY: Flurries. Accumulation 10-15 cm. Ridge wind light from the southeast. Temperature near -1. Freezing level 700 m.
Avalanche Summary
No new avalanches have been observed during the past week; however, an avalanche cycle is expected on Sunday.
Snowpack Summary
A widespread melt-freeze crust exists on all aspects and elevations. How well the incoming new snow bonds to this crust will be a critical determinant of avalanche danger on Sunday.Below the snow surface, the upper snowpack is well-settled and bonding well to the late-November rain crust. Below tree line the snow pack is thin and there are many early season hazards. Snowpack depths range from 30 cm at 800 m elevation to 180 cm at 1220 m.
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.