Eastside Region

Lawinenprobleme

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  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1–2.5

  South - Southwest winds have been consistently blowing snow for the past 24 hours. With ample snow available for transport, unstable wind drifts have developed at all elevations on leeward slopes. Winds continued to howl overnight as certain areas in the region received new snow, allowing for even larger wind slabs to form. Blowing snow and cornice formation are key indicators of wind slab formation. Hollow, stiff, textured snow can clue you into where this problem lies. You’ll likely find it beneath ridgelines, in gullies, on open slopes, in cross-loaded bowls, and in open areas below treeline. These wind slabs have developed on a variety of surface types which may affect their reactivity. We are thinking both natural and human-triggered wind slabs are on the menu today. It is important to remember that a wind slab avalanche could step down to our buried weak layers and trigger an avalanche involving the entirety of our snowpack. Stick to low-angle terrain without overhead hazards to minimize your exposure.

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1.5–3

  We are still talking about buried weak layers at the base of our snowpack. Depth hoar and buried facets have shown variability in depth and structure throughout our forecast region. In areas where the snowpack is generally deeper, such as along the crest, and in the Mammoth and June Lake areas, we are seeing limited signs of instability, such as cracking and wumpfing. However, the weak structure still exists, and is vulnerable to human trigger near shallowly buried trigger points, and natural loading. An avalanche on these layers in these areas could break deeper than 6 ft, and would almost certainly be unsurvivable. 

  In other areas where the snowpack is generally shallower, we have seen reactivity in response to loading, including wumpfing, cracking, and slopescale collapsing. An avalanche on these weak layers could be fairly easy for a human to trigger, and is more susceptible to failing naturally under a new load. Be wary of shallowly buried trigger points such as rocks, bushes, steep rocky faces, and convexities, as well as wind loaded areas and the runouts of start zones. Persistent slab avalanches can be triggered remotely, so your best bet is to avoid traveling on, above, or below 30º slopes.