Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
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: Expect the warmest temperatures of the winter, so far. Warming, sun, and old weak snow layers at will maintain dangerous conditions. Choose your routes with these in mind. Step back if you find signs of instability such as shooting cracks, hear whumphs, or find slabby snow over weaker snow.
Snow and Avalanche Discussion
As we round out January, the sun is becoming stronger already. This may have caused a small wet loose avalanches on sunny slopes holding cold snow.
A storm on the 23rd 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.
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.
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.