Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

Stormy weather will continue to impact the Snoqualmie area Sunday night and Monday. Warming temperatures, strong winds, and heavy snowfall may create an upside-down snowpack at the surface. Steer around open slopes greater than 35 degrees to avoid the avalanche hazard.

Lawinenprobleme

  • Storm Slabs

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

    Warming temperature, high precipitation rates, and strong winds may turn additional new snow into a slab over the lighter, dryer, and weaker snow that fell this weekend. You could see avalanches fail at this new interface on Monday. Handpits and uptrack-tests can highlight weak snow layers and help you located the avalanche problem in the terrain. Expect thicker and potentially easier to trigger slabs on wind loaded slopes. Steer around open areas greater than 35 degrees at mid and upper elevations. 

    Below treeline less snow and mild temperatures will limit storm slab development. Pay attention to convex rollovers, very steep slopes, and rocky terrain where these thinner storm slabs may still occur. If you find yourself near or below the rain-snow line, don’t be surprised to see piles of rollballs or even very small loose wet avalanches.

    (3/21/2021) Uptrack tests like this can be performed by any mode of travel. They can highlight weaknesses within the new storm snow as you travel.

Avalanche Discussion

Winter-like stormy weather continues to impact the Snoqualmie zone. Since 3/18, 6-12” of snow has fallen at mid-elevations around the Pass. Recent snow occurred with cooling temperatures and light/moderate winds resulting in a generally soft and unconsolidated surface. On Sunday, significant amounts of weak graupel were observed in the surface snow.  An additional foot or more of snow may accumulate over this  interface by mid-afternoon on Monday. You could see isolated natural avalanches especially during periods of heavy precipitation or blowing snow. While avalanches may entrain some of the recent snow, we don’t anticipate slides failing below this new interface. Any avalanche issues should remain above the 3/18 crust. 

The thickness of the 3/18 crust depends largely on aspect and elevation. On slopes that receive more direct sunshine and lower in the terrain, this curst may be very thick and strong. At upper elevations and on more shaded slopes, the crust could appear very thin, weak, and sometimes unnoticeable. 

Cornices continue to grow sharp and overhanging. On Sunday, several small natural cornice collapses were observed. Stay well away from the lip of these looming waves of snow. They often fail much farther back than you may anticipate. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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