Watch out for slopes being warmed by direct sun. This may locally raise the avalanche danger.
Weather Forecast
Sunday: Clearing up and becoming sunny. Light winds. Freezing level around 900 m.Monday: No snow. Sunny breaks. Light winds. Freezing level around 1200 m.Tuesday: Light snow. Light S winds. Freezing level around 1000 m.
Avalanche Summary
A widespread large natural avalanche cycle is suspected to have occurred on Friday, but poor weather limited observations, especially of alpine terrain. Numerous size 1-2 slabs were triggered naturally and by skiers directly, remotely, and sympathetically at and below treeline. These failed on either storm slab weaknesses or buried persistent weak layers.
Snowpack Summary
Low density snow had high density snow or rain (depending on elevation) piled on top of it at rapid loading rates during the recent storm. Storm totals are around 1m of snow (over 100 mm of rain below about 1500 m). Storm slabs were very touchy on Friday. Strong southerly winds have shifted snow into wind slabs and hard wind-pressed surfaces in exposed terrain. A weakness of surface hoar and/or a crust exists within the upper snowpack, which has been reactive over the last week, creating very large avalanches. Cooling is expected to help stabilize the snowpack quickly at low elevations, and more slowly at upper elevations. Direct sunshine may trigger some further shedding of storm snow on Sunday/Monday. The lower snowpack is well settled.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.