Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Limite del bosco
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In sintesi

Conditions are sketchy. Skiers and riders remotely triggered powerful avalanches from hundreds to thousands of feet away 5 of the past 6 days—expect more of the same today. Avalanches will be larger and more destructive as you gain elevation and move into wind-affected terrain. Traveling safely even near avalanche terrain is difficult—build in extra safety margins.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–3

    The Persistent Slab problem is unusual in how many recent avalanches we've seen in middle elevation terrain (view Observations). In areas sheltered from the wind, expect to find 1-2.5 foot thick slabs. In terrain affected by the wind, you'll find much denser, 2-5 foot thick slabs. The avalanches are failing on a variety of weak layers: surface hoar, facets, and crust+facet combinations. Large natural and human-triggered avalanches have been observed on most aspects. Assume this problem exists on all upper and middle elevation slopes and on shadier, lower elevation aspects.

    The avalanches described above could "step down" to weak snow near the ground, producing much larger, unsurvivable avalanches. At least 2 avalanches did so this week in the Banner Summit zone (watch video). This layer of weak snow near the ground exists in upper elevation terrain and on most shaded middle-elevation slopes (W-N-E). 

    Some facts to help you travel safely today:

    • You can trigger avalanches remotely—from flat or gentle terrain below, above, or to the sides of steep slopes.
    • Avalanches can break well above you, either while you are descending or at the bottom of a slope.
    • Avalanches are pulling back into relatively flat terrain above steeper slopes.
    • Some recent avalanches were hundreds to thousands of feet wide.

    (1/19/2024) This photo shows several large avalanches that were remotely-triggered by riders in the Beaver Creek drainage. The furthest away slide is over 800 feet wide, and failed a half mile from where the avalanches were triggered, out of sight on the right side of the photo.

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Smaller avalanches involving only the snowfall since the last big storm could release naturally (on their own) and trigger the dangerous Persistent Slabs described above. These avalanches should not be large enough to bury people unless you are above terrain traps (creeks, roadcuts, etc). You could see several types of smaller slides today:

    • Dry or wet loose snow avalanches: This morning's sunshine could be enough to trigger sluffs. These are most likely at middle and upper elevations, on very steep slopes that directly face the sun. Small cornice fall or a little wind-blown snow can also trigger these slides. These will be most common in the western mountains that have seen more snowfall and less wind in recent days.
    • Wind slab avalanches: If you're traveling in exposed upper elevation terrain, you may find and trigger small pockets of wind-blown snow.

    The photo shows a natural avalanche that appeared to be triggered by a tiny wet avalanche or rollerballs coming from above, indicating how easy it is to trigger Persistent Slab avalanches. Pay attention to what's above you as you're traveling. 

    (1/23/2024) Natural persistent slab avalanche in the Gladiator Creek drainage (9300' SW-W). This slide appeared to be triggered by wet snow or avalanches from above. 

Avalanche Discussion

Conditions remain scary. Consistent snowfall following the large January storms has not given the snowpack a chance to stabilize. The spate of large, remotely-triggered avalanches in the past week are a flashing red neon sign saying "Be Careful!"

You will encounter two different snowpacks in this zone — a lean one and a fat one. Both can produce deadly avalanches. Some details:

WOOD RIVER VALLEY: The mountains around the Wood River Valley have received the short end of the snowfall stick this season. These hills remained almost completely brown during early-season storms, with snow beginning to accumulate in December. Today, you'll find 1-2 feet of snow on the ground on shaded slopes at middle and upper elevations. Despite the thin snowpack, many slopes now have a slab perched above weak snow near the ground (see Ethan's Observation from the mountains near Hailey, and the photos below). In recent days, the Sun Valley Ski Patrol reported widespread cracking and collapsing  as they worked to evaluate and prepare closed terrain. Last Friday, they remotely triggered an avalanche on an E aspect at 8,300' in closed, unskied terrain. If you are feeling adventurous and head out looking for turns in this area, expect to find sketchy avalanche conditions anywhere you find enough snow to ski or ride. 

DOLLARHIDE to the SOLDIERS: The western part of this zone has a much deeper snowpack, including at lower elevations. Dollarhide Summit has 4 feet of settled snow on the ground. Here, and west into the Soldiers, you'll find a snowpack that resembles that found in the Sawtooth & Western Smoky Mtns forecast zone. The snowpack extends to the valley bottoms, and the avalanche problems do too. 

All of this zone has a lot of small, not-so obvious avalanche paths at lower and middle elevations. Many of these end in terrain traps (road cuts, narrow gullies, and creek bottoms). While this enticing terrain can be friendly when stability is good, it is deceptively hazardous on days like today. This week, many avalanches piled up debris in terrain traps. As you gain elevation you'll find increasingly thick slabs, especially in wind-affected terrain.

What's the point: Be suspicious of steep slopes at all elevations. Slides can break in surprising locations, extend into low angle (less than 30*) terrain, and be wider than expected. Be aware of  people near, above, or below you;  accidentally triggering a large avalanche on another group is a real possibility. 

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