Summit Lake

Lawinenprobleme

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–2

  At upper elevations in areas receiving high winds with loose snow on the surface wind slabs are expected to form on leeward slopes. These are most common near ridgelines and prominent terrain features. Keep an eye out for deeper pillows of wind transported snow and look for shooting cracks or small avalanches on test slopes as a warning sign for unstable wind slabs. Typical wind slabs are 6-12" deep but can be deeper in gulley features or depressions. 

  There are a few potential weak layers near the surface in Summit Lake that could make wind slabs more reactive to the weight of a skier. These include buried surface hoar and facets on top of ice crusts. Remote triggering is possible when wind slabs bury existing weak layers, which is when a person initiates an avalanche from an adjacent low angle slope.

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  2–3

  Above 2000' there is a wide range of snow depth in Summit Lake creating a wide range of snowpack structures. In areas with a thinner overall snowpack, the potential to trigger an avalanche on a layer of facets near the ground still exists. This type of avalanche is often triggered from a thin spot in the snowpack, like on the edge of a wind loaded gully, and then propagates across the slope. On slopes receiving active wind loading the added stress of the wind transported snow may cause buried weak layers to become more reactive to human triggering.  

  To evaluate this problem you can use a ski pole, probe, or hand pit to keep track of the overall depth of the snowpack and how easy it is to break through the icy crusts as you gain elevation. Once it is possible to break through the icy crusts or if the crusts disappear entirely (above ~2500') the likelihood of being able to trigger a buried weak layer will increase. Using hand pits or snowpits to dig down and assess weak layers within the snowpack is the best way to evaluate this problem. However, persistent weak layers are tricky to evaluate even for avalanche professionals. To avoid this problem you can always stick to lower angle slopes or try to select locations with a deeper snowpack where the weak layers are less concerning and buried deeper.