Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dense, heavy snowfall, rain, and strong winds are stressing a weak snowpack. Large avalanches are likely, especially where wind is drifting snow. Stay off of and out from below all steep wind-loaded terrain. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes.

Conditions are most dangerous in the Soldier Mtns and Dollarhide Summit area where more snow and rain fell overnight.

Avalanche problems

  • Persistent Slabs

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

    Dense snowfall (Storm Totals page), rain, and wind (Mountain Weather Forecast) are pushing the layer of weak, faceted snow buried 1-2 feet deep over the edge on some slopes, especially in the western part of this zone. What should you expect to see out there?

    • Large, destructive avalanches could release on their own (natural avalanches), especially in wind-loaded terrain. Some slides may be large enough to break trees. 
    • Remotely triggering slides from below, above, and to the sides of steep slopes is possible.
    • Small, thin wind slab avalanches that release near ridgelines could "step down", failing on weak faceted layers deeper in the snowpack and becoming much wider than the initial avalanche.

    Following the last storm, we observed plenty of avalanche activity in this zone and surrounding areas (see observation from the Soldiers, Wood River Valley, and in Bassett Gulch). Ben's video (click here) recapping events of the past few days before this storm is definitely worth a watch.

    We urge backcountry skiers and riders to continue to choose low angled slopes and to pay extra attention to the terrain they're adjacent to. Remotely triggering an avalanche from below, above, and to the sides of steep slopes remains a very real possibility.

    Build some extra safety margin into your travel plans today. The Lake Ck avalanche (photo to right/below, click here for video) that released Sunday or Monday was over a quarter-mile wide and should be treated as foreshadowing, not as an outlier event. 

    ADDITIONAL DISCUSSION: Today's expected strong winds will form drifts and slabs in exposed terrain. Some slabs will be touchy (sensitive to triggering) and could release naturally. While some of the fresh wind slabs will pose a threat on their own, the bigger concern is how they impact the weak faceted snow discussed above. Relatively small wind slab avalanches could "step down" as they move downhill, failing on layers deeper in the snowpack and becoming much wider than the initial avalanche. 

    (1/11/2021) Very large persistent slab avalanche on the headwall at the back of Lake Creek. Crown is at least 1000' wide. Based on earlier observations it likely failed between 1/10 and 1/11. Expect more of this type of activity with this storm.

Avalanche Discussion

SCALES OF SPATIAL VARIABILITY

Much of today's forecast is "painted red", showing HIGH danger. Does that mean every slope, cirque, or drainage in our 3200 square mile forecast area is going to behave the same? Heck no. On the broad scale associated with backcountry avalanche danger ratings, spatial variability causes avalanche problems and danger to change as you move from one location to another. Let's look at a couple of ways conditions may differ within and between zones:   

  1. Within the Soldier & WRV Mountains zone: We view Avalanche Warnings and HIGH danger as "sledgehammers": blunt tools designed to perform a simple task. We avoid nuanced messaging when big, stomping natural or triggered avalanches are crashing down in the mountains.  A potential pitfall exists with the sledgehammer approach when a forecast zone has areas that are obviously meeting HIGH danger criteria (upper elevations in the Soldier Mtns and the Smoky Mtns crest/Dollarhide Summit area west of Ketchum and Hailey) versus areas that are still dangerous but lack the "in your face" natural avalanche activity (the mountains within a few miles either side of the highway between Ketchum and Bellevue, and the foothills in the Little Wood River drainage). If someone put a gun to my head and told me I had to ski or ride an avalanche path in this zone right now, I'd choose one as close to Hailey, Bellevue, or Carey as possible because 1) it snowed less  2) avalanches will be smaller  3) avalanches may not be as easy to trigger. A big caveat: I’d rather be forced to walk across Main Street in Ketchum or Hailey while blindfolded than ski or ride steep, consequential avalanche terrain near Ketchum.  
  2. Avalanche problems/behavior between and within zones: In the Banner Summit area and northern Sawtooths, the weak layer of faceted snow that has been causing problems all season is now over 3 feet deep. Read the Banner Summit Deep Persistent Slab Problem Discussion for the good, the bad, and the ugly repercussions. Now, contrast that with the widespread natural and remotely triggered Persistent Slab activity over the past week throughout the Smoky Mountains.

We try to provide as much information as possible each morning, but it’s important to recognize that the Forecast products cover large areas; they are designed to serve as a starting point, and you get to make the ultimate decisions about how and where to play.

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