Lawinenlagebericht

Snoqualmie 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 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A fast but potent storm will cause the avalanche danger to quickly rise Friday morning. Avalanches may fail easily at or just above a scratchy crust on steep open slopes. These slides will become much more dangerous in wind-loaded areas and when you find more than 6-8 inches of new snow.

Lawinenprobleme

  • Storm Slabs

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

    It will take a few hours for the storm slab concern to develop Friday, but start tracking it early. If you see signs that the new snow isn’t bonding well or that it’s burying a weak surface anticipate the danger getting worse as the slabs thicken. Several factors point toward the potential for storm slabs. The most notable is the chance for this snow to accumulate on a firm crust and possibly surface hoar or facets. High precipitation rates, strong winds, and a bump in temperatures mid-day could all lead to even greater instability. 

    Fortunately, these shallow slabs should be easy to test. Use small slopes, hand shears, and uptrack tests to monitor the new-old interface. If you see cracking or blocks slide easily, steer away from steep slopes. This includes openings in the trees where these slides may run in normal “safe” areas. 

    If you crest out into exposed slopes, blowing snow could create much larger and more dangerous avalanches on the lee side of ridgelines. Give wind-loaded terrain a very wide berth.

    (12/12/2024)

    Using a small test slope produced cracking and blocks of failing snow. An indication that slabs may exist in nearby similar terrain.

    Photo: Andy Harrington

  • Loose Wet

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

    Near the rain-snow line you might see natural loose avalanches releasing from very steep slopes or as snow falls out of trees. Warm sticky snow, rollerballs, and other avalanches all point toward this issue. A bump in temperatures mid-day could make these slides more likely. These avalanches should be generally small and easy to manage. Just don’t let one shove you into a creek or gully.

    (12/28/2024)

    Eacmple: Small wet loose activity on a road cut in the eastern half of the zone near Stampede Pass. You could see similar wet activity on Friday. 

    Photo: Dallas Glass

Avalanche Discussion

Friday’s storm isn’t huge, but it will be an abrupt change from conditions over the past several days. With precipitation arriving at or just before sunrise, there may not be much hazard to start the day. A 2-3 inch (5-8cm) crust on the surface should pretty much eliminate any avalanche danger. However, heavy precipitation rates will quickly cause the hazard to rise. You could even see a very shallow natural avalanche cycle during periods of heavy snowfall.

It will be interesting to see how well the new snow sticks to the old surface. In some places, surface hoar and facets were observed prior to the storm. If these weak grains survive the wind, they could make for very touchy conditions. 

Prior to this storm, travel conditions were very challenging. Breakable crust, icy slopes, frozen tree bombs, and piles of avalanche debris. It will take more than a few inches of snow to make these hazards disappear.

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