Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
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The Bottom Line: We've added a substantial amount of new snow to the snowpack of the East Cascades, and lots of avalanche activity has been observed. With the added load, large avalanches may be easier to trigger on multiple deeper weak layers. Avoid avalanche terrain if you see signs of instability such as shooting cracks, or hear whumphs. When the sun comes out, watch out for loose wet slides on steep sunny slopes.
Snow and Avalanche Discussion
The East Central Cascades picked up from 2.0" to .3" of snow water equivalent, depending on location. Snow accumulated rapidly as heavy snow fell and the temperatures warmed up, this caused a widespread natural avalanche cycle throughout the Cascades. Many large paths ran in the area, entraining wet snow as the debris ran through the water saturated lower elevation snowpack. Most of these appear to have ran within the storm snow, but some may have taken out persistent weak layers. It appears that it rained up to around 5,000ft, but uncertainty remains regarding how far down the water percolated into the snowpack.
Recent large slide off the north side of Wedge Mountain that entrained wet snow and broke some burned trees.
Problems
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.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
