Salt River and Wyoming Ranges

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

  Wind slab avalanches will be easy to trigger today. There has been fresh snow over the past week accompanied by enough wind to move the new snow around. This recent weather has created slabs up to 3 feet in depth. Two people have been caught and carried in avalanches in the last two days in backcountry terrain adjacent to Jackson Hole Mountain Resort; similar hazards exist across the Greys forecasting zone. 

  The wind has transported snow onto a variety of old surfaces, several crusts were formed in the top meter of the snowpack and make for a great sliding surface. This structure is widespread. It is easy to be surprised by wind slabs as they can form in unexpected pockets. Watch out for snow surfaces that appear loaded or pillowy, cracking is an obvious sign of instability.

  

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  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Unlikely

  Größe

  2–3

  Weak snow that formed in December persists at the base of the snowpack across the entire Greys River forecast zone. However, the thickness of the hard slabs that overlay this weak snow varies based on geographic location. In the Salt, Snake River, and deeper portions of the Wyoming Range, these weak layers are buried 3-5+ feet deep making it unlikely for a human to impact them. In shallow parts of the forecast zone, such as the far eastern side of the Wyoming Range, these slabs are only 2-3 feet thick making it more possible for humans to trigger avalanches on the buried weak layers. Shallow, rocky, and unsupported terrain on the north half of the compass is where you are most likely to impact weak layers. Keep in mind that a large trigger such as a cornice fall could trigger one of these very large avalanches, even in areas where the snowpack is deep.

  Identify thin areas in the Greys River zone as you ride. Probing or digging can provide useful information about the depth of the weak layers preserved at the bottom of the snowpack. This evaluation is critical if you are riding in a shallow part of the zone. A total snow depth of less than 5 feet (150cm) is a red flag.

  The last reported human-triggered avalanche involving deeply buried weak layers occurred on March 9th on the far eastern side of the Wyoming Range.