Bulletin d’avalanche

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Sawtooth Avalanche Center
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Danger d’avalanche

Thu
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

A powerful storm is creating very dangerous avalanche conditions. Destructive natural and human-triggered avalanches are very likely to release in windy terrain. Avoid steep slopes where the wind is drifting snow, and any steep terrain receiving significant rain.

Problèmes avalancheux

  • Wind Slabs

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

    You are very likely to trigger 1-3 foot thick slabs in wind-loaded terrain. Avalanches could release naturally, and cornices could fail, triggering slabs on the slopes below.  The size and chance of avalanches will increase as you climb into windier terrain at upper elevations. Avalanches could be wider than you expect, and very easy to trigger where storm snow buried slick crusts, crusts + facets, or surface hoar.

    Today's wind will blow strong from the SW and W, forming slabs in many areas. Look for them near or below ridgelines, along mid-slope ribs, and on aprons beneath chutes. Cracks shooting out in front of your sled or boards mean you've found a sensitive slab. You can manage your exposure to this problem by identifying and avoiding wind-loaded slopes, including the gentler terrain below large, upper elevation starting zones.

  • Persistent Slabs

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

    Today's storm plays out on a stage set by our Persistent Slab problem. Intense loading rates (snow + wind) and naturally occurring Wind Slab avalanches (Problem 1) are increasing the odds of a much larger Persistent Slab avalanche. 

    These are most likely on NW-NE-E-SE facing slopes at middle and upper elevations (near and above ~8500' in this zone), holding both thick slabs and suspect crust + facet combinations.

    Avalanches involving these layers could be very large and likely unsurvivable. Persistent Slabs often break wider than you'd expect, and can be triggered remotely—from gentler terrain above, below, or to the sides of steep slopes.

Avalanche Discussion

Today is a good day to avoid avalanche terrain, including middle and low elevation runouts of large avalanche paths. Strong to extreme winds and heavy snow will combine to make very dangerous avalanche conditions in areas affected by the wind. Avalanche hazard should peak this morning with the passage of a powerful cold front before noon. Avalanches involving new storm snow will be dangerous on their own, but they also increase the chance of very large avalanches breaking on persistent weak layers buried deeper in the snowpack. Adding to the mix, pre-cold front rainlines may briefly climb to around 8,200'. Expect naturally occurring wet avalanches anywhere you observe significant rain on snow.

Régions couvertes