Galena Summit & Eastern Mtns

Lawinenprobleme

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Very Likely

  Größe

  2–3

  Parting clouds yesterday revealed the aftermath of the recent snowpocalypse: a widespread and extensive cycle of large natural avalanches. Avalanches were most numerous in the southern portion of this zone that had the weakest snowpack and the greatest storm totals. Countless slides occurred in the Eagle Creek, Murdock, and N. Fk. Big Wood drainages (including Durrance). Large avalanches were also observed in the Smokys (near Baker Lake, Anderson Cr, Owl Cr, Titus Ridge area) and in the Boulders (Boulder Peak, Silver Peak, Gladiator). Check out the Media section below for a visual sampling of the activity.

  Some of these slides failed on the December facets that have been a problem all winter. But others broke on persistent weak layers that were on the surface before this recent storm, and possibly on intermediate layers between the two. Observers on Galena Summit yesterday reported poor snowpack test scores on the weak layer just beneath the recent storm snow, and there were numerous reports of snowpack collapsing. Wasn't life simple when there was just one weak layer?! 

  It'll take some time to tease out the pattern of new persistent weak layers. While our snowpack may be complex, decision-making is simple. Avoid avalanche terrain. Avoid being on, below, or near steep slopes. 

  

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  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  1–2

  The recent storm brought strong winds along with extensive ammunition for drifting. Yesterday's improved visibility provided some unique examples of what strong, sustained winds can do with several feet of low-density new snow. The drifts, dunes, and scallops formed by the wind may be visually interesting to us, but our weak snowpack is not a big fan. The extensive wind drifting is adding more stress to the persistent weak layers described above, making wind-affected slopes even more dangerous. But now we're just talking different shades of scary, and the travel advice remains the same as for the persistent slab problem: Avoid avalanche terrain.

  ADDITIONAL DISCUSSION:Warming temperatures and sunshine today are likely to produce natural loose snow avalanches within the recent storm snow. As these sluffs run downhill, they could trigger larger (and much more dangerous) persistent slab avalanches.