Continental

Problemi valanghivi

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  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1.5–2.5

  The recent north wind has formed wind slabs 1-2+ feet deep on the lee side of high elevation ridge lines, terrain features, and cross-loaded gullies.  These have formed on top of heavy storm slabs which may allow them to remain susceptible to human triggers.  Collapsing beneath old wind slabs has been observed as recently as 2/2 pointing toward the possibility that wind slabs remain possible for a person or machine to trigger in specific locations.

  These recently formed wind slabs have been observed to be decreasing in sensitivity as they stiffen and gain strength.  Watch for signs of instability such as shooting cracks or collapsing that would indicate that it remains possible to trigger an avalanche.  These can be identified by having a pillowed look to them and smooth or rippled texture.  At this point, these will be 1 finger to knife hard and have a hollow drum-like feel.

  Rain crust that formed at the tail end of the 1/28 storm has limited wind redistribution to some extent where it exists.  Its presence and extent is variable though.  It has been found up to 1700' below Keystone Canyon, does not exist north of the canyon in the lowe river flats, but goes up to 3500 feet at Moonlight Basin.  It is also not present as you move north from Thompson Pass.

  

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1.5–2.5

  In areas protected from recent north wind, storm snow from 1/28 remains top-heavy in some locations.   Clear and cold nights have allowed up to 3 feet of new snow to settle somewhat, slowly creating better structure with decreasing sensitivity in stability tests.  The new/old interface appears to be well bonded as well although wind slab avalanches will still have the possibility to step down to this interface.  This has not yet been observed but could be a possibility.  There has been some natural avalanche activity as a direct result of outflow winds, however, it is unclear if any slides have stepped down to this interface. 

  We will keep this avalanche problem on our list until more data can be gathered.  However, at this point, it appears sensitivity is decreasing and this avalanche problem will not be long lasting.

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  Glide Cracks

  • Tutte le quote

  Probabilità

  Unlikely

  Dimensione

  2.5–3

  Glide cracks exist in a few places in all three of our forecast zones.  Town Mountain and Mile High hold the highest concentration of these.  A few glide cracks have released over the last month creating large destructive avalanches.

  The sensitivity of Glide avalanches is not possible to predict.  These release independent of snowpack stability.  Instead of being affected by changes in the surface snow (loading, warming, etc) like all other avalanche problems, glide avalanches are tied to a more complicated relationship between the underside of the snowpack and the friction at the ground.  This interaction is not well understood.  What is well understood is that this avalanche problem produces deadly avalanches that include the entire snowpack and can release spontaneously.

  Travel advice is very simple: avoid spending time under glide cracks.  Glide cracks are generally easy to identify as they look like crevasses, but exist in non-glaciated terrain.  New snow and wind will make identifying these more difficult, as they may have been covered.