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

  Likely

  Dimensione

  1.5–2.5

  The ongoing north wind event has formed deep windslabs on the lee side of terrain features, with numerous natural avalanches 2-3+ feet in depth observed.  Some of these naturals failed at deeper layers in the snowpack (see problem 2).  

  Wind loaded slopes will be more stubborn to triggers today, but the depth of slabs, combined with the possibility of a wind slab stepping down to a known persistent weak layer will keep the hazard at considerable.  Users are reccomended to use conservative terrain choices today and avoid travelling on freshly wind-loaded slopes and exposure to terrain traps.  Current wind slabs will have a hollow drumlike feel, and often have a pillowed look.  Signs of instability such as shooting cracks or collapsing are a clear sign that instability exists and users should move to slopes less than 30°.

  Ice Climbers: Today is not a good day to travel into terrain traps like Sheep and Bear Creek.  There are large snow slopes above you that could fail naturally and bury you and your party.  The strength of the winds has created sensitive slabs at low elevation in some places that are large enough to knock you off your feet on even small snow slopes.  Pay attention to if snow slopes exist on your climbing route and what the overhead hazard is.

   

   

  

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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

  Likely

  Dimensione

  2.5–3

  Several deep natural avalanches occurred during peak wind intensity on 2/20, with the 1/26 interface being the expected weak layer.  The most significant slide was noted on the SW face of Averys.  Another notable slide was seen in the upper slope of Skate Park/ East and the front side of Little Girls/South.  These are both popular areas for backcountry skiing and snowmachining and continue to show the presence of a persistent weak layer that is capable of producing large avalanches.

  Recent wind has changed the character of the slab above the weak layer making assesment more challenging for users.

  Conservative terrain choices are recommended due to the combination of freshly wind loaded snow and uncertainties regarding the sensitivity of the 1/26 interface.

   

   

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Unlikely

  Dimensione

  2.5–3.5

  A deeply buried weak layer near the ground remains a low-likelihood, high-consequence problem—especially in steep, rocky terrain and areas where the snowpack is thin or highly variable. Triggering this layer directly is unlikely at this time, but avalanches that start in the upper snowpack could step down to the basal weak layer.  There is a high degree of uncertainty regarding poor structure at the base of the snowpack.  What we can be sure about is that this layer is less of a concern in the Maritime zone and more so as you move towards the Continental zone where the snowpack is thinner and the weak layer is more developed.

  Watch for thin spots near rock outcrops, scoured features, and along ridge tops. Wind loading adds stress to these shallow areas, and we don’t know where the tipping point is.