Watch for fresh winds slabs and avoid shallow spots where triggering deeper layers is more likely.
Confidence
Low - Due to the number of field observations
Weather Forecast
SATURDAY NIGHT: Mostly cloudy with isolated flurries, trace accumulation. Moderate to strong west wind. Freezing level valley bottom, alpine low temperature -8C.SUNDAY: Mostly cloudy with flurries later in the day. Light northwest wind with moderate gusts. Freezing level climbing to 1200 m, alpine high temperature -6C.MONDAY: Overnight flurries with skies clearing throughout the day, around 5 cm accumulating by Monday morning. Light west-northwest wind. Freezing level valley bottom, alpine high temperature -8C.TUESDAY: Cloudy with sunny breaks. Moderate west wind. Freezing level valley bottom, alpine low temperature -13C.
Avalanche Summary
Skier traffic produced a few small (size 1) avalanches in the new snow on Thursday.The most recent reports of larger avalanches are from last weekend, when warm temperatures stressed the deeper layers in the snowpack and produced a few size 2 avalanches.
Snowpack Summary
10-20 cm new snow is being redistributed by strong winds are forming wind slabs in the alpine and treeline. This new snow is burying large surface hoar crystals and/or sun crusts, which could eventually develop into a touchy problem as snow accumulates. The most suspect terrain features will be steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist). Large variability in snow depths still exists in the region, ranging from almost no snow to nearly 200 cm in some areas. For average snowpack areas, expect to find weak and sugary faceted snow around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack has been the culprit for large avalanches in the region over the past few weeks.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.