Galena Summit & Eastern Mtns

Lawinenprobleme

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1.5–2.5

  You could trigger 1-4 foot thick avalanches on buried weak layers (sugary facets or crust + facet combinations). This video from the Soldier Mountains illustrates the problem (video). The steady stream of snowfall and windblown snow has many slopes teetering on the edge, just waiting for a trigger.

  The distribution, character, and sensitivity of the weak layers vary from slope to slope. You can't thread the needle today; don't get cute. Your best bet is to assume this problem exists and choose terrain accordingly. Conditions are most dangerous where wind slabs and drifts have formed a thicker, more cohesive slab. However, the snowfall from the past couple of weeks has become cohesive enough to act as a slab on most sheltered slopes. In steep, craggy terrain, slabs often form on the aprons of chutes and couloirs and in cirques beneath large cliff bands (photo). 

  You can reduce your risk by avoiding slopes steeper than 30 degrees—especially large avalanche paths and those with ugly consequences if you are caught in a slide. Persistent weak layers can fail unpredictably and break significantly wider, deeper, and higher on slopes than you might expect, producing much larger avalanches. You could remotely trigger avalanches from gentle terrain above, below, or to the sides of steep slopes. Avalanches could be triggered by the second, third, or fourth rider on a slope.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1–2

  Triggering a large wind slab avalanche is likely at upper elevations. Low density snowfall and moderate SW-S-SE wind over the past 36 hrs combined to build fresh, sensitive slabs. An increase in wind speeds this afternoon will only add to this problem. Many wind slabs rest atop persistent weak layers (read Problem #1 above). Because of this, the slabs you encounter have the potential to break wider, deeper, or higher above you than a "simple" wind slab.

  Wind slabs will be larger and more dangerous at upper elevations but may also exist in wind-affected middle elevation terrain. Look for them near ridgelines and mid-slope terrain features like ribs and gullies. You've likely found a wind slab if the soft, light snow you're moving through suddenly becomes heavy (dense) or you run up onto snow that is stiff and supports your weight. Cracks shooting out from your skis or sled and collapsing of the snowpack are both clear indications that the slab is unstable.