West Slopes North

Lawinenprobleme

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  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Very Likely

  Größe

  1–3

  While other areas of the Cascades experienced rarely seen avalanche activity on Thursday, the storm really gets into full swing in the West North tonight. Expect to see 2-3’ of new snow by the time heavy precipitation backs off Friday morning. Anticipate avalanche danger to be higher near and south of Highway 20 where significant snowfall is forecast to last the entire day.

  3000’ snow levels and the dense new snow that falls at those temperatures are normal for this region. What is different - and potentially more dangerous - is this new snow is falling on a cold, dry snowpack that could struggle to adjust to rapid loading. In addition to the usual avalanche activity in the new storm and wind slab layers, there is also the possibility we could see avalanches that break into deeper layers, entrain large amounts of snow and run long distances.

  On Friday simply avoid exposure to avalanche terrain, especially during and immediately after periods of heavy snowfall and strong winds earlier in the day. Wind speeds are forecast to lower slightly in the morning but could become strong again in the afternoon. This will further the danger on leeward slopes.

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  3

  Heavy snow the next 24 hours could trigger very large avalanches on a layer of surface hoar buried prior to Christmas. We’ve had several storms since then and the layer is probably between 4 and 7 feet deep - and that is before adding another 2-3’ of new snow from this storm. These avalanches could release with a load of new snow combined with wind loading, or a smaller avalanche could step down and trigger a much larger avalanche at this layer. 

  This is just one more reason to avoid all avalanche terrain on Friday. Be aware that large avalanches from higher terrain could run into lower elevations where avalanches are not normally seen.