Sawtooth & Western Smoky Mtns

Lawinenprobleme

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Very Likely

  Größe

  1–2

  Natural and human-triggered wet loose avalanches are likely on steep, wind-sheltered slopes directly facing the sun.

  • These slides often initiate near the base of trees, rocks, and cliffs, starting as small point releases and entraining snow and fanning out as they move downhill. These slides could trigger larger slab avalanches (example) as they move downhill.
  • The majority of these slides will involve only the recent snowfall, but they can grow large enough to knock you off your feet or sled and carry you where you don't want to go. Even small slides are surprisingly difficult to escape and are consequential above terrain traps such as gullies, creeks, and trees.
  • Rollerballs (video), pinwheels, and wet, slushy snow surfaces are clear signs the snow is heating up; wet avalanches may follow. Avoid lingering under big avalanche paths and steep, rocky slopes while they directly face the sun.

  Additional Discussion - Cornices: Cornices could break on their own as they sag during the heat of the day. Natural cornice fall can trigger both wet loose slides and the larger slab avalanches described below.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1.5–2

  It is possible to trigger large slabs in wind-loaded terrain, especially at upper elevations on slopes facing the northern half of the compass. 

  • Recent winds built wind slabs below corniced and exposed ridgelines, on the sides of cross-loaded gullies, and in cirques below steep faces, large cliff bands, and chutes. These are most common at upper elevations but also exist in middle elevations and may be found lower on slopes than expected.
  • Look for smooth snow pillows, dunes, textured snow surfaces, and cornices. Feel for stiff snow and listen for hollow or "drummy" sounds.
  • Wind slabs are fairly easy to identify and avoid. Snowpack cracking and collapsing are clear signs of unstable conditions. Give cornices a wide berth; they can break on their own or with the weight of you or your sled.

  Additional Discussion - Persistent Slabs:  You could trigger a much larger, 2-4 ft thick persistent slab avalanche on buried weak layers (sugary facets, surface hoar, and crust + facet combinations). Recently wind-loaded, middle and upper elevation slopes facing NW-N-NE-E are most suspect. Don't expect to experience obvious signs of instability; the first clue could be the avalanche you trigger.