Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
The most likely places to trigger a slide today are on upper elevation slopes facing the north half of the compass where avalanches may break up to 2' feet deep, failing on a persistent weak layer of facets generally found about a foot above the ground.
Common characteristics (1) The snowpack is generally weak, rotten, and full of facets. (2) Strong winds have blown from nearly every direction, forming hit-or-miss wind slabs on top of this weak, sugary mess.
What does all of this mean? Below treeline, the snowpack is basically one big persistent weak layer lacking a slab on top to create an avalanche. Near treeline snow depths increase some, and there is more of a slab on top of the weak snow, but they aren't nearly as sensitive as they were last week.
Photo - north aspect near 10k feet. Snow layers near the shovel blade is snow that fell in November and early December. The weakest snow is the obvious stripe of facets near the top edge of the shovel blade. That stripe of weak snow sits on a decomposing crust. Snow near the shovel handle is the slab that can create an avalanche. Slopes with the added weight of wind drifted snow on top of this layering are the ones most likely to avalanche.
Today you'll want to look for signs of unstable snow like cracks shooting out in front of you, sudden collapses of the snowpack, or loud whoomphing sounds.