Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering a large, destructive avalanche is more likely here than in neighboring zones. You're most likely to trigger a slide on slopes with wind drifts or stiffer snow at or near the surface. You can significantly reduce your risk by choosing terrain that is sheltered from the wind. As the day warms up, wet snow avalanches are possible on very steep slopes that face the sun.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    Weak, grey, sugary facets and crusts exist on shaded NW-N-NE-E facing slopes at middle and upper elevations. This layer sits near the ground under 3-5 feet of snow. In neighboring zones, the persistent slab problem has faded to join the list of minor concerns. The Galena Summit & Eastern Mountains are an unfortunate outlier. 

    Here, the chance of triggering a large persistent slab avalanche is still very much a possibility. Watch Ben's video from the White Clouds on Tuesday where he describes a snowpack that's "capable of creating large, destructive avalanches". 

     Yesterday in the Pioneers, a local professional backed off a ski objective because of this layer. "If the structure wasn't enough to close it [the run], the test results backed up that it's still possible for that layer to propagate." It's been only a week since our last major loading event and this layer is not likely to notably improve any time soon.

    This large, natural avalanche released naturally near the end of the last storm in very steep, rocky, wind-loaded upper elevation terrain in the 4th of July drainage in the White Cloud Mountains.  

Avalanche Discussion

IT'S DIFFERENT HERE

Splashes of green (LOW danger) have appeared on many elevation bands in the surrounding zones. In this zone, we're much more hesitant to go there. Why?

  1. A proven weak layer. We've observed persistent slab avalanches failing near the ground after each of the three major storms of the season. 
  2. The weak layer is ugly. Sugary facets remain weak and continue to produce unstable snowpack test scores. 
  3. The weak layers are well distributed. Due to the overall higher elevation, old October snow is located in more terrain here than in neighboring zones. 
  4. More trigger points exist. This zone has seen enough snow to build a meaty, dangerous slab, but not enough to completely armor the weak layer from the impact of our weight. 

The combination of these factors adds up to keep triggering a persistent slab avalanche squarely on the table. It's also plenty of motivation to keep me and other local professionals off of wind-affected, "prime time" 35-45* slopes where this weak layer exists.

In addition to the persistent slab problems listed above, there are a couple of other minor problems to consider when planning your day in the mountains:

Wet Loose Avalanches - Wet loose avalanches were reported each of the last two days on very steep, sunny slopes. The sun will be out from daybreak to dinner in most areas and these slides are possible again today. Wet loose avalanches begin at a "point", usually the base of a warm rock or tree, and fan out to collect snow as they go. They are most problematic in confined terrain or on large slopes where they gather a lot of snow. Rollerballs, or herds of small snowballs peeling off steep terrain, can be a helpful clue that the snow's surface is weakening and wet loose slides may occur. 

Wind Affected Snow - Southwest of this zone, Soldier Mountain Cat Ski staff triggered a sizeable avalanche with explosives on Monday (photo). If you go poking around on enough very steep, wind-sculpted slopes you may find small, isolated wind slabs that are sensitive to your weight. This problem can persist longer in areas where slabs rest on icy surfaces or a persistent weak layer. This same, wind-affected terrain harbors very large cornices. Extended periods of near or above freezing temperatures may encourage these unpredictable, massive blocks of snow to sag and fail.

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