Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Expect a major change in snow and avalanche conditions over the next 48 hours with heavy snow, warming temperatures, and rain over the weekend. You can trigger slab avalanches in, and possibly just under, the new snow. If you experience shooting cracks or loud collapses in the snow, stick to slopes under 35 degrees. 

Lawinenprobleme

  • Storm Slabs

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

    Look for indicators that the new snow is cohesive and could break as a slab. If you see cracks shooting through the snow, stick to lower-angle terrain. Use small test slopes to see if the snow slides easily before committing to bigger terrain. You may also be able to trigger slab avalanches on leeward slopes at upper elevations where east winds formed slabs on Thursday. In wind-sheltered areas, you may still be able to trigger avalanches on recently buried interfaces in the top 2 feet of the snowpack.

    Temperatures will get increasingly warmer as the day progresses. Expect that the new snow may become more cohesive and easier to trigger.  Be alert to changes in avalanche conditions throughout the day and as you move through the mountains. 

    (12/20/2022)

    Many small (D1) soft slab avalanches observed. Henry Creek.

    Photo: Ryan Minton

Avalanche Discussion

The incoming storm will bring even warmer temperatures as we enter the weekend. It remains to be seen just how warm it will get and if (or how much) it'll rain. Wet snow or rain on snow could bring very dangerous avalanche conditions on Saturday. We anticipate that the weather models may be challenged by this unique storm and temperature scenario.

Over the past two days, observers in the Henry creek area reported cracks shooting long distances through the snow and audible collapses, though less so on Thursday. A layer buried on Dec 18th has been slow to bond due to very cold temperatures. On Tuesday, observers reported easily triggering many soft slab avalanches in the upper portion of the new snow.

On the 18-20th, Stevens Pass picked up lots of very light snow with 3-day 24-hour totals reaching nearly 3 feet. With all the new snow, falling in tree wells and holes around creeks and boulders can be dangerous. Keep your partners in sight and within earshot.

The December 18th interface holds weak grains of small facets, surface hoar, and crusts on southerly aspects. I found easy, sudden shears in snowpack tests on this interface on Monday. You may also find the December 8th surface hoar layer another foot lower in the snowpack. Weak layers, buried in late November, can be found near the bottom of the snowpack around a couple of crumbly crusts. While they haven't been involved in avalanches in over a month, a very big storm could activate them.

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