Banner Summit

Problèmes avalancheux

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1–2

  Expect to find fresh wind drifts and slabs up to 3 feet thick in exposed, upper-elevation terrain.  Today's strong wind and snowfall could produce natural avalanche activity. Watch for dunes or smooth pillows below ridgelines and cornices and on the sides of cross-loaded gullies.

  Fortunately, the fresh wind slabs should be easy to spot and avoid. If you feel the surface snow getting stiffer, move to gentler terrain. Cracks shooting out from your skis or sled are an obvious sign that you've found a wind slab. Natural releases and human-triggered slides have the potential to trigger the much larger Persistent Slabs described below as the wind slab avalanche moves downslope.

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Unlikely

  Taille

  2–3

  Weeks of heavy, dense snowfall, rain, and warm temperatures formed thick, meaty slabs on most middle and upper elevation slopes. Multiple crusts may be buried in the upper 3 feet of the snowpack, providing possible failure layers where the crusts are relatively thin.

  Assume the slab + weak layer (crust) setup exists on all slopes until proven otherwise. You may not experience obvious signs of instability—like snowpack collapsing or cracks shooting out from your skis or sled—before triggering an avalanche. 

  As you change elevation and aspect, or travel through different drainages, you'll see significant variability in the buried crusts. This uncertainty makes it challenging to accurately predict which slopes could still cause trouble. There's an outside chance you could trigger avalanches remotely—from flat terrain below, above, and to the sides of steep slopes. 

  Additional Discussion: Weak, sugary, faceted snow in the bottom third of the snowpack is now buried 3-6 feet deep on W-NW-N-NE-E-SE facing slopes at middle and upper elevations. Triggering a huge slide on these layers is unlikely but would be unsurvivable. You're most likely to poke this beast in windy and/or rocky areas where the snowpack depth is variable.