Continually reassess conditions as you travel into avalanche terrain and be aware of the potential for deeper weaknesses in the snowpack.
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Wednesday
Weather Forecast
MONDAY: Mainly cloudy / Light to moderate east wind / Alpine temperature -3 / Freezing level 1300mTUESDAY: Flurries, accumulation 5cm / Light to moderate south wind / Alpine temperature 0 / Freezing level 1700mWEDNESDAY: Flurries, accumulation 5-10cm / Light to moderate south wind / Alpine temperature 0 / Freezing level 1600m
Avalanche Summary
On Saturday, explosive control and ski cutting produced numerous small storm slabs (size 1-1.5) and two size 2 storm slabs up to 50 cm deep. Most failed within the storm snow, but a few on the mid-March rain crust.On Monday, wind slabs may remain reactive in human triggers and the deeper mid-February weak layer continues to present a low likelihood of triggering yet would produce a large avalanche and thus a high consequence if triggered.
Snowpack Summary
Roughly 30 cm of storm snow now sits above a widespread rain crust up to 2200 m. Thicker wind slabs and large cornices likely exist in alpine terrain. Reports suggest the storm snow is generally well bonded to the crust, and cooling temperatures should help stabilize the upper snowpack. The mid-February crust/facet layer is now 80-120 cm deep and may be up to 200 cm deep in wind loaded terrain. This layer was reactive prior to recent warming events, but now there's some uncertainty as to how long it will remain reactive.
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.
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.