Continental

Lawinenprobleme

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  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–2

  Our forecast area received 12-16 inches of snow on Thursday night.  This shot of snow was accompanied by strong winds that were predominately from the south although direction was changing during the storm.  Expect a variety of aspects to be loaded.   A break in precipitation and falling temperatures on Friday allowed the snowpack to settle a bit. Although, heightened avalanche conditions still exists on specific terrain features.  These areas include the lee side of high elevation ridge lines that were exposed to strong south storm winds Thursday night and cross loaded terrain.  Steep convex terrain is likely still sensitive as well.

  On Friday previous heavy wind redistribution was observed on south aspects in close proximity to Thompson Pass.  Wind drifts up to 3 feet in depth were found on the lee side of terrain features.  These did not show much energy.  Tested a few wind loaded slopes steeper than 30° without result.  

  Test the sensitivity of wind loaded storm slabs in the area you choose to travel before exposing yourself to consequential terrain.   Use small incosequential test slopes and hand pits to determine how well the new snow is bonded.  Signs of instablility include shooting cracks, collapsing and natural avalanche activity.

  A couple inches of snow may fall today, this is not expected to affect stability.

   

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–2

   In some areas there is a layer of buried surface hoar that is now buried by 18-24 inches of snow.  Where this layer exists expect storm slabs to be more sensitive to human triggers.  Buried surface hoar exists below 4000' in areas that were protected from the strong outflow winds of last weekend.  The strength of winds last weekend would have destroyed this layer in most locations, although is still a concern in isolated areas.  It is likely that areas in close proximity to Thompson Pass will not have buried surface hoar.

  Tested some slopes where surface hoar was previously reported without signs of instability.  Distribution and sensitivity of the 12/6 buried surface hoar layer is unclear at this point.  We are assuming that it exists in isolated locations, but has not yet been identified.  The only natural avalanche activity observed on 12/8 was a windloaded pocket that released from extreme terrain in the upper elevations of 40.5 mile peak.

  The most likely place to encounter buried surface hoar as a problem layer would be steep protected slopes close to the 3000' elevation band.

  It is also possible that the upper elevations of the Continental zone are harboring a persistent weak layer. Although, its sensitivity, depth and distribution is unclear at this point.