Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Very dangerous avalanche conditions exist. Skiers and riders are likely to trigger large, destructive avalanches. Wet avalanches are possible on slopes that face the sun. Choose conservative terrain and build in a large safety margin. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    Triggering a wind slab avalanche is possible in recently wind-loaded terrain. Wind slabs will be larger and more dangerous at upper elevations but may also exist on wind-affected middle elevation slopes. Look for smooth pillows of windblown snow near ridgelines, mid-slope gullies, and lower in cirques below large cliff bands and on the aprons of chutes and couloirs. Cracks shooting out from your skis or sled and collapsing of the snowpack are both clear indications that you've found a wind slab. Wind slabs or a failing cornice can serve as an effective trigger for the much larger and more dangerous persistent slab problem described above. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3.5

    You are likely to trigger a 2-5' thick persistent slab avalanche. Buried weak layers (sugary facets or crust + facet combinations) were overloaded by recent snowfall, wind-blown snow, and rain, producing hundreds of avalanches in recent days (map). Many slopes remain on the brink of failure, simply waiting for a trigger to push them over the edge.  Slabs will be more sensitive to triggering where recently wind-loaded. You can identify these slopes by the stiffer, denser snow that keeps your skis or sled from sinking deep into the snowpack.

    Unfortunately, you can't out-smart this problem with small-scale route finding. Today is not the day to try and thread the needle. This is the type of problem that may not offer obvious signs of instability, like snowpack cracking or collapsing. Tracks on a slope do not mean it's safe. Avalanches can be triggered by the second, third, or fourth rider. They may break over 1,000' wide and several feet thick, running full-path to the valley floor. If caught, many of these slides will be unsurvivable.

    You could remotely trigger avalanches from gentle terrain far above, below, or to the sides of steep slopes. Use caution today. Travel in upper elevation avalanche terrain is not recommended. 

    (3/12/2023) This persistent slab avalanche released just off Highway 75 on the N side of Galena Summit. 

Avalanche Discussion

Last weekend, a snowmobiler was tragically killed in an avalanche. The danger was not obvious. As they rode in, their group did not observe any nearby natural avalanches or other signs of instability like snowpack cracking or collapsing. The fatal slide was not triggered by the first or even the second rider on the slope. It was a sunny, beautiful day following a large recent storm. Today is a carbon copy of that day. Please be careful out there.

The conditions you experience at low elevation trailheads this morning are far from what you should expect as you climb in elevation or as temperatures warm into the afternoon. Here are some considerations as you plan your day:

  • As you climb, so does the danger. Expect to encounter a host of avalanche problems at middle and upper elevations. It may finally start to feel "spring-like" around town in the Wood River Valley, but don't be fooled, the mountains still have a layered, mid-winter snowpack. If you're driving to Galena Summit, the danger is real, and it begins right from the road (photo).  If you start the day at low elevation, expect the danger to sharply increase as you climb out of areas with stout crusts and enter terrain with thick, dry slabs and recently wind-blown snow. In addition to the persistent slab and wind slab avalanche problems discussed above, large sagging cornices guard the rims cirques. These massive overhanging chunks of snow are unpredictable and can spontaneously release. They are dangerous in their own right but may also trigger a slab avalanche as they tumble downslope. 
  • Warm days = wet avalanches. Yesterday, clouds clung to many locations north of Galena Summit. This means today may be the first time some slopes soak in the sun. Anticipate wet avalanches this morning beginning on SE aspects before following the sun through the southern sky. A hard freeze last night may have turned some low elevation slopes into an ice rink (photo). This time of year, however, the hot sun can soften surface crusts and pump water into the snow. This process increases the odds of both wet loose avalanches and wet slab avalanches in the afternoon or evening before the snowpack has a chance to firm up again overnight (photo). Keep this in mind if you plan to be out late in the day, especially if your return route brings you through or beneath W, SW, or S-facing terrain. 

Today's avalanche conditions demand your respect and attention. It's a day when you can feel like you're doing everything right, get comfortable, and inadvertently stray from your plan. Get out in the mountains and enjoy this beautiful day, but don't let your guard down. Keep your objectives conservative as the snowpack adjusts to recent storms. 

Regioni coperte