Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Sensitive wind drifts exist in terrain exposed to the wind. Larger avalanches involving layers of weak snow buried 1-3' beneath the surface are most likely in steep, wind-affected terrain, but are possible in sheltered terrain as well. Avalanches involving these weak layers can be triggered from long distances away from steeper slopes. You can significantly reduce your risk today by sticking to gentler terrain sheltered from the effects of the wind.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Several weak layers exist in the upper few feet of the snowpack. These layers have produced avalanches and continue to produce collapsing and unstable snowpack test scores. Triggering an avalanche involving these layers remains a real possibility today. You're most likely to do this in steep terrain that has been recently wind-loaded, but this problem exists in sheltered terrain as well. These weak layers involve either a crust+facet combination, small facets without a crust, or surface hoar. You'll need a slope that faces the sun in order to have the crust, but the facets and surface hoar can be found around the compass.

    We've looked for and found these layers across our forecast area, but they don't exist on all slopes. In places, the sun and the wind helped to mute the effects of some of these layers, but in others they are well preserved and quite concerning. Avalanches on persistent weak layers can be triggered from long distances away from steeper slopes ("remote triggering"). They can break wider than you might expect and pull back into gentler terrain above steeper slopes. 

    Want to significantly decrease your risk of triggering a large avalanche today? You can do so by sticking to gentler terrain, free of overhead hazards, that is sheltered from the effects of the wind. As a bonus, you'll also find the best skiing and riding here.

    ADDITIONAL DISCUSSION - WEAK SNOW NEAR THE GROUND: A layer of weak, faceted snow exists near the base of the snowpack. This layer has produced hundreds of avalanches this season, including the large slide I remotely triggered yesterday in the Baker Creek drainage (photo at right/above, details here). An even larger slide was remotely triggered 5 days ago by riders in the White Clouds (photos and details here). In this zone, this weak snow is now buried 2-4 feet down, beneath a dense slab of snow. Impacting deeply buried weak layers with your weight isn't easy, but the consequences are grave. You're most likely to trigger this layer in wind-affected alpine terrain where the snowpack depths are variable. Here, you'll have better access to this weak snow. This is exactly the type of terrain where I triggered the pictured avalanche yesterday. Digging down to this weak snow with the track of your sled is another "great" way to impact this deep weak layer.

    (12/30/2022) This large avalanche was remotely triggered from 400-500' away on the ridgeline above. It broke 1-2' deep on a S-facing slope at 9,500', failing on the weak snow near the ground that exists across the forecast area.This slope had been heavily affected by previous winds.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Yesterday's storm brought 5-10" of new snow to this zone, accompanied by periodically gusty winds. In exposed terrain, where the wind was blowing hard enough to transport snow, you will find sensitive wind slabs. These slabs are most likely in upper elevation terrain but may extend down into middle elevation terrain as well. Soldier Mountain Cat Ski intentionally triggered several wind slabs yesterday during routine control work. Similar slabs continued to grow with additional snow and wind overnight. 

    Look for evidence that the wind has been at work as you travel. Has the new snow been knocked out of the trees? Are you seeing textures on the surface, like drifts and dunes and ripples? What about fresh cornice growth? These are all signs the wind has been transporting snow and that you should be looking for wind slabs. Cracking and collapsing in fresh drifts are sure signs you've found a sensitive slab. Slabs are most likely near and along ridgelines, and near terrain features like gullies that get cross-loaded by the wind.

    Triggered slabs have the possibility to step-down to the deeper weak layers described above. The result would be a much larger and more destructive avalanche.

Avalanche Discussion

In a strange way, avoiding avalanches is much easier when things are obviously dangerous. The snowpack gives us lots of feedback that is hard to ignore, including cracking and collapsing, and both natural and human-triggered avalanches. Unfortunately, it is during times of decreasing danger that most avalanche accidents occur. The obvious red flags occur less frequently and the temptations of steep slopes covered in powder become harder and harder to ignore. This is exactly the situation we find ourselves in now.

For much of this season, entering avalanche terrain hasn't even been an option. You click into your skis and start walking and are immediately triggering collapses. Or maybe you are riding along you see snow get shaken off of the trees in every open meadow you approach. These signs are impossible to ignore. Today, when you head into the backcountry, you have a good chance of not getting that sort of feedback. You might spend hours skinning through untracked snow and not experience a single collapse. Let me assure you, the problems haven't disappeared, they've just become gradually less likely. 

Here's how my day went yesterday: I rode my sled through many meadows and didn't feel a single collapse. I parked the sled and started skinning along and didn't see any recent avalanches and didn't experience any collapsing of the snowpack. There was a blanket of soft powder everywhere I looked, and I could feel myself being drawn to it. I understand, we are all snow lovers. I stopped to dig a pit and found what I expected to find: several weak layers of snow, all producing unstable snowpack test scores. I continued up the slope, walking above steeper slopes, imagining skiing the snow below. I knew there was a decent chance I could ski one of those pitches and not trigger a slide, but the possibility of it was more than enough to keep me out of avalanche terrain. 

I summited the peak I was on and skied down a different low-angle ridge from the one I had climbed. I was at the bottom of my run when I made a hard turn to stop, and I felt a deep, sharp collapse. I then heard a tearing sound as if huge pieces of velcro were being torn apart. I looked at the slope behind me and watched as a large avalanche cascaded down into the runout below, breaking small trees and piling up snow deeply. I had no plans to enter avalanche terrain that day, but watching a slide in action has a way of reaffirming that commitment. Think of this story when you are in the mountains today, and spend some time imagining what would happen if you or your partners were caught in a large slide in the terrain you are in. If you choose to enter avalanche terrain you are choosing to accept these consequences. We are not out of the woods yet.

Regioni coperte