Central Cascades

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  With more new snow coming in and winds shifting from west to southwest, expect new wind slabs building on lee slopes. 

  Utilizing small safe test slopes is a good way to look for cracking in the slab. Cracking, along with signs of recent avalanches, are good indicators this problem is present in the terrain. 

  Remember, wind can pile up snow many times deeper than the snow dropped by the storm. As wind slabs become deeper, avalanches can become larger.

  Look for signs of wind transported snow in clearings and areas of sparse or dead trees below treeline. 

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  No big updates with this problem from previous days except the weak layers that make up this problem are getting deeper.

  There are multiple persistent weak layers beneath the recent storm snow. Buried facets and buried surface hoar can be found 3-6' below the surface. The new incoming snow will add stress to these layers.

  Earlier in the week, observers reported experiencing slope collapses and whumphs. However, this is a tricky problem in a sense that as the persistent weak layers become deeper we may receive less feedback in the form of whuphs and collapses. They will be less likely to trigger, but it is not out of the question. The slab on top of these weak layers is substiantial and could result in a large to very large avalanche if triggered. 

  Persistent slabs can be remotely triggered and can propagate across terrain to a larger extent compared to other slab types.

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Avalanches releasing in the recent storm snow layers are possible. This problem will build overnight and through the day on Saturday. Be cautious in steep terrain especially above terrain traps. As you move through the terrain, look for cracking in recent storm snow on small convex and steep test slopes. Cracking in the slab is a good indicator that avalanches in the storm snow layers can happen.