A widespread avalanche cycle is ongoing. Large avalanches are reaching the end of their runouts. Conservative terrain choices (tree skiing) and avoiding exposure to overhead avalanche hazard are highly advised.
Weather Forecast
Light to moderate precip is forecast today with strong to extreme westerly winds at ridgetop. A warm front will pass through the region overnight bringing moderate to heavy precip, with another 15-20cm and sustained winds expected through Tues. Snowfall and winds should taper off through Wed as an arctic ridge builds through Thursday.
Snowpack Summary
Nearly 70cm of snow has fallen in the last week, with 35cm over the past 2 days. Winds have increased overnight, rapidly loading lee slopes and forming windslabs in the alpine. There are several reactive layers in and below the storm snow. The Nov 28 persistent weak layer is down 70 and gives sudden planar results in snowpack tests.
Avalanche Summary
A widespread natural cycle and avalanche control are ongoing. Natural avalanches size 2.5 to 3.5 have been occurring from all aspects and running to the end of their runout zones. Several avalanches were reported from skiers up Connaught yesterday, running off of Mt Cheops and to within 20m of the uptrack on the other side of the valley.
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.
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.