Bulletin d’avalanche

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
Voir sur la carte

Danger d’avalanche

Sat
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
Open full map
Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You are very likely to trigger avalanches large enough to bury a person in many areas. You may be able to trigger avalanches remotely—from flat terrain below, above, and to the sides of steep slopes. Conditions are the most dangerous in the southern half of this zone.

 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–2.5

    Slabs formed in early February rest above a variety of ugly, widespread, weak layers (facets, surface hoars, crusts, and combinations). You are most likely to trigger a 2-4 foot thick avalanche where:

    • The slope or terrain you're connected to is steeper than about 35 degrees
    • The slope faces the northern 2/3 of the compass
    • The slab is less than about 3' thick—relatively shallower spots may exist where the wind frequently blows, and the slab is not uniformly thick.

    Before triggering an avalanche, you may or may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. We can't assume tracks on a slope mean it is safe; several people could descend a slope before triggering an avalanche.

  • Storm Slabs

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

    Last night's storm brought heavy snowfall capable of producing avalanches large enough to bury people.  These reactive storms slabs will be widespread, and should be easy to trigger—don't rule out the possibility of these slides occurring naturally as snowfall continues today. 

    Slabs will be thicker, and stiffer in windier terrain near ridgelines or terrain features exposed to the wind. These types of avalanches could break wider than expected and entrain a lot of snow. Watch for signs like snowpack cracking or collapsing, this is the bull's-eye information that you have found this problem. Any storm slab that releases could "step-down" into more deeply buried weak layers, causing an even bigger avalanche (see Persistent Slab problem).

Avalanche Discussion

Heavy snowfall and warming temperatures overnight have built thick slabs of storm snow, 1 to 2 feet deep. Freshly built slabs will be easily triggered by a skier or rider and could be large enough to bury you. Where the wind has transported snow into thicker drifts, these will be larger and more consequential. Avalanches could break larger than expected, and triggering a slide remotely—from flat terrain below, above, or to the sides of steep slopes—isn’t out of the question. Watch for signs of instability, like cracking or collapsing in the surface snow—this is clear evidence that you have found the recipe for an avalanche. Expect the size and likelihood of triggering a slide to increase at middle and upper elevations, where storm totals are greater and the wind has been moving the new snow.

Avalanches breaking deeper in the snowpack are certainly not out of the question with the added weight of this storm. Continued reports of collapsing throughout the forecast area show that the snowpack needs more time to adjust to the load from early February storms. Recent snowfall over the last 24 hours is adding to this load, effectively resetting the clock on that adjustment. Professionals across the forecast area have expressed concerns about the lingering possibility of triggering a large, thick avalanche. 

Today, you can reduce your chances of triggering an avalanche by avoiding travel on or below steep slopes and seeking out lower-angle slopes free of overhead hazards.

Régions couvertes