Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Small 6-10 inch deep avalanches were easily triggered by humans along steep mid and upper elevation ridgelines on Thursday as temperatures increased and wind shifted the snow around. It is uncertain how reactive these deposits will remain on Friday. Search for and avoid steep areas where you find heavier pockets of snow showing signs of weakness such as cracking or other nearby avalanches.

Lawinenprobleme

  • Wind Slabs

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

    Slab avalanches are your largest concern right now. They may continue to remain reactive on Friday, or they could become stubborn and tougher to trigger.  You can find these stiffer snow deposits in mid and upper elevation areas along ridgelines, on other leeward surfaces, and around rocky outcroppings. Identify signs of recent and active wind drifted snow: blowing snow, drifted features and cornices, textured surfaces or thicker, hollow feeling snow.

    Check how the snow is reacting by traveling out on small test slopes such as cut banks before exposing yourself to bigger terrain. When you’re testing or first entering slopes, start from the top of the slope so that snow will not come down from above. If you see cracks shooting out in front of you, or any signs of avalanches, big or small, stay off terrain steeper than 35 degrees. Even small avalanches can have big impacts if you’re in high consequence terrain, when there are trees, cliffs, or gullies you might get pulled through or into.

    (12/8/2021) If you see long shooting crack they are indicators that avalanches could occur on steeper slopes.  Photo: Matt Primomo

Avalanche Discussion

Several observers reported small loose dry surface avalanches, or “sluffs” on Wednesday.  These were usually triggered by a person as they entered steep terrain. Despite slab development on Thursday, sluffs could still occur in some areas of low-density snow. These could knock you off your feet, or surprise another person if they are below you on a slope. Try to limit exposures in steep terrain to one person at a time. 

About 5 feet of snow fell in the Stevens Pass Zone in the last week, taking us from zero to hero and abruptly starting the season off. Mostly small avalanches with a few larger ones thrown in occurred during the storm and are continuing to occur since the main event. Most are limited to upper snowpack layers. Before Thursday’s warming event where slabs formed, observers told us many of the snow surfaces were just cold, dry, low-density powder. That may have already changed, and is not expected to continue this weekend as a slightly warmer storm passes through. 

Beneath the past week’s storm snow sits a stout crust (formed in late November) making up the bottom of the snowpack on slopes above 5000ft. The December 8th crust is resting just above that and is intermittent up to at least 6,200ft. Observers reported variable tests on both crusts in some areas. In areas on the eastern side harboring cooler temperatures and a thinner snowpack, stay aware of these layers as any weakness may continue to develop. As we receive snow over the weekend we will watch these layers closely.

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