Recent wind and warm temps have formed wind slabs at Treeline and above. These slabs sit on a particularly weak base this winter, which will be extremely slow to improve. Backcountry users need to adopt a conservative mindset and make cautious terrain decisions for the foreseeable future.
Continuing SW winds and warmer temps will continue the growth of wind slabs. If triggered the wind slab is very likely to steep down to the deeper instability.
This layer should be monitored as elevation is gained. Despite being labelled as deep, it can be a ways off the ground. Entrainment is a major concern. These avalanches could run to valley bottom.
No new avalanches observed or reported today.
Up to 5cm of fresh snow overlies a new rain crust formed yesterday up to at least 2200m. The upper snowpack has gained some density with the warm temps. Wind slabs are present in Alpine and exposed Treeline terrain, particularly just below ridgelines and in gully features. Below this new snow and wind slabs the snowpack is very weak. Forecasters are tracking the Dec 16th surface hoar/facet layer down 10 to 20cm and the mid-November facet/surface hoar/depth hoar layer down 50 to 80cm. If avalanches are initiated on these layers they will likely step to ground through the very weak basal facets/depth hoar. It's not a pretty picture!
Light flurries overnight with more of the same through Wednesday. Accumulations will likely be around 5cm. Mild temps and moderate SW winds are forecasted, with a cooling trend later in the week.
More details can be found in the Mountain Weather Forecast.
