Continental

Lawinenprobleme

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1.5–3

  Long periods of cold, dry, and windy weather have created weak snow surfaces that are now buried under wind slabs of varying thicknesses. The last several weeks of windy weather have created quite a bit of variability with slab thickness and surface snow texture. Hard, persistent (Wind) slabs have been observed to be a meter or more deep on the leeward sides of specific terrain features through Thompson Pass. A recent human-triggered avalanche on lower "Little Girls"  (3/25) is an indication of this problem.  

  This can be a hard problem to assess and will be stubborn to trigger. Slopes may support multiple travelers before producing an avalanche. Signs of instability with this problem will be limited due to the hardness of the slabs as well as the deep burial of weak layers in some areas. Thinner slabs will be more likely to be triggered by a human or machine and could propagate into deeper areas, as shown in the attached picture. Smaller avalanches will also have the possibility of triggering deeper weak layers in the snowpack. The best way to mitigate this problem is to choose simple terrain, ride slopes one at a time, and avoid terrain traps at the bottom of steep slopes. Avoiding steep convex terrain on the leeward sides of terrain features is recommended, especially if you see signs of previous windloading. 

  

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  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–2.5

  We are gradually coming out of an unseasonably cold stretch of weather. Isolated avalanche activity related to solar warming over the last week has been observed in some areas. As temperatures creep higher over the next week, we expect to see an increase in this activity on the south-to-west aspects. Keep an eye out for moist snow, small loose snow avalanches, rollerballs, and failing cornices, as sunny slopes warm in the afternoon hours. If you observe any of this activity, you can expect hazards to increase with additional sun exposure. 

   

  

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  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Unlikely

  Größe

  2.5–3.5

  Weak snow near the ground is increasingly common as you move North through our forecast zones, with the Continental zone being the most concerning. Although it still remains unlikely to trigger this layer, areas that have been scoured from strong northeast winds now have a shallower snowpack, making this layer closer to the surface and potentially easier for a rider to trigger.

  This is a low-likelihood but high-consequence problem most likely to be triggered in steep, rocky terrain and areas where the snowpack is thin or scoured. 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 the poor structure at the base of the snowpack.