Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

You are most likely to trigger avalanches where the wind has formed drifts or stiffened the snow surface. The fresh slabs are thickest and most widespread in upper-elevation terrain. While not likely, large avalanches failing on weak snow deeper in the snowpack are possible in wind-swept, rocky, alpine terrain.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    Triggering a large persistent slab avalanche on weak, sugary facets buried deeper in the snowpack would take some bad luck. The video to the right/above describes this problem. Where are you most likely to find this scenario? On slopes with all or most of the following characteristics:

    • Wind-swept alpine terrain, especially in the Pioneer, Boulder, and White Cloud Mountains. The White Clouds appeared to receive the most snowfall yesterday and deserve some extra respect, but strong to extreme winds blew in alpine terrain throughout this zone.
    • Steeper than about 35 degrees.
    • Variable snowpack depths with areas less than 2 feet deep and/or rocks poking through the snow surface.
    • Large, hard wind features somewhere on the slope.

     Don't expect to see or hear obvious signs of instability (snowpack collapsing or cracking) before a large avalanche releases. Snowpack stability tests are of little use in situations like this. The best way to manage this problem is to avoid terrain that checks all or most of the "boxes" above. 

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    What is it? You could find fresh wind slabs up to about a foot thick in exposed terrain. Yesterday, we observed several natural avalanches near Smiley Creek (photo to right/above) and one just above the road on Galena Summit (photo below). The erratic, W-NW-N-NE winds of the past 36 hours may have formed both soft and hard slabs. Wind slabs could overlie weak facets or crusts—especially on SE-S-SW aspects—and be more sensitive to triggering than you might expect. Due to the hard crusts beneath the recent snowfall on more southerly-facing slopes, even small avalanches could run farther and faster than anticipated.  

    Where is it? Look for wind-blown snow below exposed ridgelines, on the sides of gullies or chutes, and near large terrain features. Wind slabs will be thickest, widest, and most common at upper elevations, especially in the northern and western portions of this zone where more snow fell yesterday.  

    How can you recognize it? Cracks shooting out from your skis or sled are an obvious sign of instability. Watch for drifts, dunes, and ripples on the snow surface. Wind slabs can have a smooth, chalky appearance and feel and sound hollow, like a drum. Wind-deposited snow will be stiffer and keep your skis or snowmobile on or closer to the surface.       

    How can you manage it? Managing this problem is simple; steer clear of recent wind drifts and slabs on slopes steeper than about 35 degrees. Hard slabs that keep you or your sled on the snow surface can behave unpredictably, breaking above skiers and riders. 

     

    (2/21/23) These wind slab and loose snow avalanches released naturally on E aspects near 10,000' in the Smiley Ck drainage, likely on Tuesday, Feb 21st. 

Avalanche Discussion

Steering clear of recently formed drifts and slabs is the most effective way to stay out of trouble today. While minor, there is one other scenario to keep in mind as you prepare to head into the mountains:

  • Loose snow avalanches: Parts of this zone received several inches of low-density snowfall yesterday and could see more of the same this afternoon. Also, the upper foot of the snowpack is extremely weak and faceted on some NW-N-NE-E facing slopes. On very steep slopes approaching 40 degrees, it won't take much to get surficial sluffs moving (photo). A little bit of direct sunshine, new snowfall, or some wind-blown snow sifting onto a steep slope could trigger natural loose snow avalanches. These probably won't be big enough to bury you, but they can pack a punch and could knock you over, pushing you where you don't want to go. Sluffs have the potential to trigger wind slab avalanches when recent winds formed stiff drifts lower in cirques and on the aprons of chutes and couloirs. 

Pay attention to the terrain above you. Even small avalanches can ruin your day in complex, high-consequence terrain. Before committing to skiing or riding that steep, beautiful-looking line, think about where an avalanche could carry you. Could you get pushed over cliffs, through trees, or into a creek or gully? Slopes with these terrain traps are inherently more dangerous than open slopes with a clean runout. 

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