Avalanche forecast

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Several days of snowfall and moderate winds have created dangerous conditions at upper elevations. Despite poor visibility yesterday, we saw several natural slab avalanches large enough to bury people. Avoid steep, exposed slopes with drifts or stiff snow on the surface. Natural loose snow slides (sluffs) are possible, especially if the sun pokes through the clouds. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    The weak snow buried near the ground continues to be the primary avalanche concern in this zone. While encountering a wind slab (described below in Problem #2) is more likely, any wind slab you trigger has a chance of "stepping-down" to the weak snow near the ground. Yesterday in Baker Creek, we saw multiple slab avalanches that were triggered by loose snow sluffs or small cornice fall. Some recent human-triggered and natural persistent slab avalanche activity:

    • Saturday, a skier on Titus Ridge intentionally triggered a large avalanche. The slide initiated as a stiff wind slab that formed during last week's wind event and then "stepped down" to the December weak layer. Photos and more details are available here. Ben investigated this event (video).
    • Sunday, Sun Valley Heli reported seeing a recent large, natural avalanche that failed near the crest of the Smoky Mtns north of Dollarhide near Baker Ck divide, likely involving this weak snow (photo here).
    • An observer reported fairly recent natural avalanche activity in the Pioneer Mtns west of Grays Peak.

    The depth of the snowpack is highly variable in this zone. In areas where the snowpack is less than about 4 feet deep, the weak layer is much more "accessible" to a skier or rider. This makes triggering slides easier. Recent upper elevation winds have scoured some slopes (bringing the weak layer closer to the surface) and deposited slabs on others (adding weight to the weak layer).

    So what sort of areas should you be most worried about right now? The avalanches described above share some characteristics:

    • Slopes steeper than about 35 degrees
    • Wind-loaded terrain
    • Rocky slopes with a thinner snowpack

     This is exactly the type of terrain where you are most likely to encounter this problem today. Recent snowfall has hidden signs of wind events in places, making it more difficult to tell when you're on previously wind-loaded slopes. This fact has made many experienced skiers and riders think twice about entering consequential avalanche terrain, despite the gradually decreasing danger. 

    (2/13/2021) This avalanche was intentionally triggered by a skier stomping on the cornices/wind slab above. It failed on an E/NE facing slope at 9,700' above Titus Lake. The slide initiated in the stiff wind slabs that formed during last week's wind event and then stepped down to the weak snow near the ground as it traveled downslope.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    With 1-2 feet of fresh snow in recent days, it doesn't take a lot of wind to form slabs. Yesterday, we saw sizable natural avalanches in alpine terrain in the Smoky Mtns (video to right/below, Observation), and snowfall and wind continued since then. Expect to find widespread wind slabs in exposed upper elevation terrain and in cirques beneath large cliff bands. Watch for and steer clear of slopes with drifting and with cornices on the ridges. 

    ADDITIONAL DISCUSSION:On very steep slopes, natural and human-triggered loose snow avalanches (sluffs) are possible. Yesterday, I saw a lot of sluffing and small cornice fall, and some of the small slides triggered sizable avalanches as they moved downslope. If the sun pokes through the clouds today, expect to see some natural loose snow avalanches. This problem is fairly simple to manage—be aware of the terrain above you, especially if it's sunny. Remember that even small slides can have high consequences if they carry you through rocky, treed terrain or push you down into a terrain trap like a gully or a creek bed.

Avalanche Discussion

Naps, Hibernation, and Dormancy

The persistent weak layers that produced extensive natural and human-triggered avalanche activity in December and January are finally showing signs of going to sleep. Unfortunately, they aren’t “out cold” yet; they appear to be stuck in limbo.

Think back to a time when you were listening to a boring teacher or professor’s lecture on an early morning when you didn’t get enough sleep the night before. The drone of the speaker’s voice continues, you are not interested, and your head begins to bob and then snap back up as you fight the urge to fall asleep. This is how our persistent weak layers are currently behaving.

When you were falling asleep in class, someone gently touching your shoulder may or may not have been enough to get your attention; this reaction (or lack thereof) is akin to the past several days of low-density snowfall falling on many slopes. However, what if your instructor poked you hard in the ribs with a pencil? You’d instantly snap out of your partial-sleep mode and be more than a little peeved, much like our weak layers on slopes where the wind is rapidly forming stiff drifts and wind slabs, or where small loose snow avalanches are running downhill.

Until it stops snowing and blowing for an extended time, I expect the persistent weak layers on some slopes to be susceptible to a pencil poke in the ribs. The difficulty lies in:

  • Which slopes are nodding off to sleep, and which slopes are “out cold”?
  • How hard is it to poke the weak layers on the slopes where they are still nodding off to sleep? How deep is the weak layer buried?
  • If I wake one of the sleepy students/weak layers up, will it be a meek 80-pound student who tells me off or a 280-pound behemoth who gives me a royal beatdown?

Our snowpack has become quite complex in the past 3 weeks, and it's nearly impossible to answer those questions on a slope-scale unless you’re an experienced professional studying and sampling the same slide paths day in and day out. As most of us don’t have either the luxury or experience to do so, we are forced to travel a little more conservatively than we’d like to give ourselves a healthy safety margin. As always, I encourage you to think about the consequences of triggering a sizable avalanche before committing to riding or skiing large avalanche paths.  

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