Bollettino valanghe

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Sawtooth Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Natural and human-triggered wet avalanches large enough to bury people or destroy structures are possible. Avoid steep slopes where you sink into a sloppy, wet snowpack. Minimize the time you spend on or below steep slopes receiving direct sunlight or rain. 

Problemi valanghivi

  • Loose Wet

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

    Natural and human-triggered wet loose avalanches remain possible. The snowpack has not frozen solidly in 48 hours, so it will not take much daytime warming, solar input, or rain to melt any thin surface crusts that formed overnight. Once the crusts break down, there will not be much snowpack structure to keep you or your machine from falling deep into an unsupportable, soggy mess.  

    Managing this problem is fairly straightforward: Stay off of and out from beneath steep slopes after the thin surface crusts melt. Pay attention to the terrain above you; while natural avalanches are far less likely than they were yesterday, they remain possible. Even small wet avalanches are surprisingly powerful, and wet loose slides make great triggers for the wet slab avalanches described below. 

    (4/10/2023) Numerous wet snow avalanches in the northern Sawtooths. ESE, 9400'.

  • Wet Slabs

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

    Many large to huge wet slab avalanches (crown depths of 4-6 feet tall and thousands of feet wide - view photos here and below) released naturally yesterday and Sunday. The avalanche activity large enough to destroy trains and houses occurred primarily on upper elevation slopes facing W-S-E. "Smaller" wet slabs that were still large enough to bury vehicles and people released on shadier, lower and middle elevation slopes.   

    Natural and human-triggered wet slab avalanches remain possible today. Wet avalanches do not need human triggers to occur; they release on their own far more frequently than dry avalanches.  

    Accurately predicting slope-scale stability for wet slab problems is one step short of voodoo. Don't try to outsmart them.

    How do we manage this problem? Avoidance is the only reliable strategy. The prudent move is to stay off of and out from beneath large or consequential avalanche paths until the snowpack becomes supportable. Avoid avalanche terrain where you're sinking into a snowpack that resembles oatmeal. A thin surface crust will not eliminate the chances of triggering one of these beasts. 

    ADDITIONAL DISCUSSION: Don't trust cornices while the warm weather is making them sag, bend, and break. Falling cornice chunks triggered many wet avalanches yesterday and could do so again today. Minimize the time you spend beneath corniced avalanche starting zones, and give cornices plenty of space if you're traveling on ridges.

    (4/10/2023) Large wet slab avalanche on McGown Peak in the northern Sawtooths. It appears to have been triggered by a smaller loose snow avalanche. 9500, E.

Avalanche Discussion

Yesterday was one of the more impressive natural wet avalanche cycles we've seen. Hundreds of wet loose avalanches released, and dozens of monster wet slabs failed. The majority of the observed wet slab activity occurred in the Pioneer and Boulder Mountains, but we saw very large wet slabs in the western Smoky and Sawtooth Mtns as well.

Do we expect the mountains to put on another avalanche show today? No. Would we be surprised if wet avalanches run to the valley floor? No, especially in terrain like the NW-facing slopes in burned areas above Warm Springs Road. 

The snowpack needs some time for the meltwater to drain or refreeze. Until that happens—likely tonight but possibly tomorrow—you'll be playing with fire if you're traveling in avalanche terrain with a wet, mushy, unsupportable snowpack. 

Today is another great day to steer clear of consequential or complex avalanche terrain. Wet snow stability changes rapidly; the slope you safely rode or crossed beneath in the morning could be ready to release naturally hours or minutes later. The mountains remain in the middle of an unpredictable spring transition, and there will be plenty of time to ride or ski fun lines once the snowpack is freezing solidly at night. 

Regioni coperte