Very warm temperatures plus precipitation on Fri/Sat could increase avalanche danger. New wind slabs will develop and the potential for the Dec week layers to wake up is still a concern.
Weather Forecast
Up to 10cm is forecast for the divide starting Fri night. Temperatures will be warm with freezing level reaching ridgetop by Saturday. Strong West winds will continue for the next three days and accompany the precip on the weekend. This means continued windslab development and rise in avalanche danger.
Snowpack Summary
The little bit of snow from the weekend has been stripped from SW slopes by strong SW winds also built slabs on lee slopes. These are sitting on temp/sun crusts, old wind slabs or facets with surface hoar in sheltered locations. Surface slabs were very reactive in tests at Forum but shears 40cm down on pervious slabs failed with only hard results.
Avalanche Summary
There was evidence of wind slab avalanches at the back of Forum lake but this was likely from a few days ago. Otherwise there has been no avalanche activity observed up to Jan 22.
Confidence
Intensity of incoming weather systems is uncertain on Saturday
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.