Avalanche danger is increasing as the storm moves into the region. The new storm snow may not bond to the recent buried weak layers.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Overnight and Sunday: Moderate to locally heavy precipitation overnight as the arctic front collides with Pacific moisture. Expect strong westerly winds ahead of the arctic air, and moderate northerly winds after the passage of the cold front.Monday: Precipitation should end during the day. Expect clearing skies and cold valley temperatures.Tuesday: Clear and cold with moderate Northeast winds.
Avalanche Summary
No recent avalanche activity has been reported. New storm slabs are expected to develop overnight. Storm slab avalanches may be easily triggered where recently buried weak layers exist. The new load of storm snow, or storm slabs in motion may cause avalanches to release on this crust layer. The most likely place you would trigger this layer is on smooth, planar, north facing slopes.
Snowpack Summary
New storm slabs are developing above weak surface layers of facetted crystals and melt/freeze crusts. These recently buried weak layers may not support the new load of storm snow that is forecast. The deeply buried early season crust continues to be a concern. There have been reports of weak sugary crystals at the crust interface that may create an easy sliding surface and allow for wide propagations.
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.