Bulletin d’avalanche

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You could trigger an avalanche in areas of recently wind-drifted or pillowed snow. It'd be a stroke of bad luck but triggering an avalanche on weak layers buried 4-6 feet deep remains a possibility on very steep, rocky, wind-affected slopes at upper elevations.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Strong, gusty NW-NE wind Tuesday afternoon and evening likely built thin wind slabs in exposed terrain. These slabs will be less touchy today, but may still be sensitive where they overlie hard, wind-polished surfaces or crusts.

    You're most likely to encounter these slabs at upper elevations. Watch for smooth pillows of stiff or hard snow, dunes, or wave-like patterns on the surface. Cracks shooting out from your skis or sled are a sure sign that you've found a sensitive slab. 

    Additional Discussion: Small, sun-induced, loose snow avalanches are possible on very steep, rocky slopes. Keep an eye on what's above you, and don't linger beneath steep terrain that directly faces the sun.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–3

    The weak layers we've struggled with all winter have not gone away but they've become less reactive to the weight of a skier or rider. Triggering a 4-6 foot thick persistent slab avalanche is becoming increasingly unlikely. Unlikely, however, is not the same as impossible. It would take a dose of very bad luck, but it may be possible to trigger one of these monsters in very steep (over 35 degrees), wind-swept, alpine terrain.  

    On Tuesday, I checked out an avalanche that failed on an east-facing slope near 8800' on Copper Mountain in the Banner Summit Zone. This slide (photo, observation) likely failed over the weekend and released on a subtle weak layer beneath our last storm snow.  Limited direct observations of this layer suggest that it's not likely an issue in the near term. That said, it's worth taking the time to dig a quick pit to see how recent snow is bonding to the older snow below.

Avalanche Discussion

LOW Danger: The Banner Summit and Wood River Valley & Soldier Zones are at LOW danger. When the danger is LOW triggering an avalanche is unlikely and most slopes are safe. Could you trigger an avalanche at LOW danger? Certainly, but you'd have to find one of the very few spots in the range with unstable snow. If you dropped 50 people off and told them to ski or ride the steepest, wind-loaded slopes they could find, someone would probably trigger a slab avalanche. It's nearly impossible to definitively predict which slope(s) are "triggerable", but we can hedge our bets by thinking about the consequences of small avalanches where we're playing. If you don't like the looks of what's below you—trees, cliffs, roads or other terrain traps—then move to a different part of the slope or another area altogether.

Today's Canvas is Tomorrow's Problem: As you head out today keep an eye on the current snow surface. Yesterday in the Soldier Mountains, I found an ugly and relatively widespread combination of crusts and facets at middle elevations (video). In relatively sheltered areas, you may notice a variety of thin crusts and "recycled powder" (facets) that sound and feel "hissy" when you're skiing or riding. This is a result of near-surface faceting caused by the combination of the sun angle and cool, winter temperatures. It's looking like we'll have some snow to celebrate this weekend. Noting the snow surface today can help you anticipate how the stability may change with minor changes in aspect or slope angle this weekend. 

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