Lawinenlagebericht

Banner Summit

Sawtooth Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

You could trigger large avalanches on steep upper elevation slopes. Natural and human-triggered wet snow avalanches are possible, especially where more than a couple of inches of snow fell yesterday or where the snowpack is less than a couple of feet thick. If you're sinking into a mushy snowpack, stick to gentler terrain and stay out from underneath large, steep slopes.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Yesterday's storm produced rain below about 8000', but you'll find dramatically different conditions up high where up to a foot of dense snowfall accumulated since Monday. Ben observed a few natural slab avalanches just above the rain line yesterday near Bull Trout Point (photos to right and below). Expect to encounter stiff drifts near ridgelines, in chutes and couloirs, and on aprons below gullies. Conditions, and possibly the snow stability, will change rapidly once you climb above yesterday's rain-snow line. While the fresh slabs should not be as easy to trigger as they were yesterday, they overlie weak faceted snow on some slopes and demand respect. Slides could break wider than you might expect.

    If the snow becomes deeper or stiffer as you're traveling, it's time to pay extra attention. Cracking and/or collapsing are indicators that you've found unstable slabs. Given the weird weather swings over the past few days, I don't trust the snowpack and will be avoiding large, consequential avalanche paths where several inches of snow fell yesterday.

    (3/1/2022) These slab avalanches failed on N/NE facing slopes at 8,300-8,500' near Banner Summit. Based on their location and the appearance of the crowns they likely failed on a layer of weak snow underneath. You can see that the bed surface has a grey/dark appearance to it, which is generally an indicator of faceted grains. Across our forecast area, weak snow developed at the surface during January and February.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Yesterday afternoon, we saw dozens of small wet avalanches in the Sawtooths and some activity in the Banner Summit area. Natural and human-triggered wet loose avalanches need to be on your radar today. In some areas, the snowpack has not frozen solidly in two or three nights. Today's warm temperatures and intermittent sunshine will create a soggy mess on many slopes. Some tips for dealing with the wet loose avalanche problem:

    • On upper elevation slopes that directly face the sun, expect to see small natural avalanches where more than a couple of inches of snow fell yesterday. 
    • If you're sinking more than a few inches into a wet snowpack that resembles the oatmeal you ate for breakfast, you'll want to stay off of and out from underneath steep slopes. Pay attention to the terrain above you in your travels, and do not linger below very steep slopes longer than needed; wet avalanches frequently release on their own.
    • Wet snow stability can change rapidly; think minutes rather than hours. The steep slope that you safely traveled on or beneath in the morning may not be stable later in the day. 
    • With wet avalanches possible on all aspects at lower elevations, creek bottoms will be spooky places to travel in or above. 
    • Slides could involve the entire lower elevation snowpack where it's thin (less than about 2 feet thick). These slides are not huge, but they are almost impossible to escape once you're caught.

    Plan your day carefully to avoid traveling through or directly above terrain traps, especially during the afternoon. 

    (3/1/2022) These wet loose avalanches failed near Banner Summit on a N-facing slope at 8,200'. They likely failed during the day on 3/1, as the rain line climbed when rain was falling on new snow.

Avalanche Discussion

SEASONAL UNCERTAINTY

A few days ago, we were freezing our butts off in the mountains. Yesterday, it was raining at 8500', and wet avalanches littered the Sawtooths and Wood River Valley and blocked Warm Springs Road. So what gives? The snowpack doesn't like wild weather swings like this. 

When I see rapid changes like those over the past few days, I dial my travel plans back. The snowpack is presenting a lot of uncertainty that didn't exist last weekend. Get out and have fun in the mountains, but you probably want to reset your "baseline" to questioning stability versus assuming it's stable until proven otherwise. The benign conditions of recent weeks are in the rearview mirror for now; add some safety margin to your plans and travel routes while the fickle spring weather continues. 

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