Watch for increasing avalanche hazard as new snow load is added to the February 27 surface hoar/ crust weak layer.
Weather Forecast
A frontal system moves through the region today bringing moderate snowfall. 15cm of accumulation is expected by Monday morning. Strong SW winds with freezing levels climbing to 1700m this afternoon. Freezing levels drop on Monday as precipitation intensity declines. A second frontal system moves in on Tuesday bringing up to 20cm by late Thursday.
Snowpack Summary
8cm of new snow sits on a breakable crust on SE through W aspects and widespread surface hoar. Soft slabs in the upper 50cm can be found near ridge crests, but are more stubborn to move now. The February 10th surface hoar / sun crust is down 50-90cm and is much less reactive than a few days ago.
Avalanche Summary
No new activity was observed in the highway corridor. We received a report of a skier triggered size 1 soft slab avalanche in Balu Pass, failing 10cm down on the February 27 surface hoar layer.
Confidence
Intensity of incoming weather systems is uncertain
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.