Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 2–3
Recent Avalanches: There were several small avalanches failing within new and windblown snow on Seattle Ridge on Wednesday. These were around a foot deep.
With another day of relatively quiet weather on tap, the biggest avalanche concern is the lingering potential to trigger a very large avalanche failing up to 2 to 6' deep on a layer of weak, faceted snow. This layer has been gaining strength, but is still showing occasional signs of concern in snowpits. The most likely place to trigger an avalanche on this layer will be a relatively thin spot where the weight of a person is able to impact the layer. This is going to be most likely in the 2500' to 3000' elevation band.
These deep slab problems are difficult to predict, and rarely give clear warning signs when conditions are dangerous. For now, the best way to manage the problem is to avoid traveling in high-consequence terrain. This includes slopes with terrain traps (cliffs, trees, rocks, gullies), as well as slopes with large, connected start zones that could produce a very large avalanche.
Dry Loose Avalanches are running fast on the previous firm surfaces buried by Tuesday's storm and will be easy to trigger in steep terrain. They may also begin to occur naturally on steep southerly aspects now that we are seeing a little bit more solar input. Keep an eye on those steep south-facing slopes, especially those with rocks or trees, which will heat up the quickest. These could also be triggered by chunks of falling cornices, which may be more likely as the sun heats them through the day.
Wind Slabs: There may still be isolated pockets of windblown snow that could produce a small avalanche today. These will most likely exist at upper elevations near ridgelines, convex rolls, and loaded gullies.
(2/12/2026)
These south-facing cornices will be important to pay attention to today. Photo from Sunburst yesterday.
Photo: Marc Heifetz