Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

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

Kernpunkte

New snow and a switch in wind direction could combine to create Wind Slabs on a variety of aspects on Friday. Keep an eye out for fresh drifts or actively blowing snow to help you identify wind-loaded areas where you’re more likely to trigger an avalanche. Don’t get caught off guard by a small slide near rocks or gullies where taking a ride could be more consequential.

Lawinenprobleme

  • Wind Slabs

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

    Wind speeds should peak in the overnight hours on Thursday night before trending downward and switching direction during the day on Friday. This means you could encounter new Wind Slabs on a variety of aspects with potentially different reactivity based on their age. Look for pillow-like drifts or areas that look “fat” compared to the surrounding terrain near ridgelines or on convex rollovers to help identify wind-loaded features you should avoid. The wind also likes to sift snow into deeper piles in confined gullies or near the base of cliffs. In some locations, you could encounter firm snow that feels hollow or notice freshly built cornices to further help key you into potentially unstable areas to steer around.

    (3/9/2023)

    The wind was sifting snow to the base of cliffs around the Snoqualmie Pass zone on 3/9.

    Photo: Andy Harrington

Avalanche Discussion

On Thursday, avalanche professionals observed moderate to strong winds drifting snow into deeper drifts on leeward slopes and the base of cliffs. The wind direction was generally from the east, with snow being transported onto different aspects than the norm. This should continue through the evening hours and into Friday morning before wind speeds start to taper and precipitation rates increase. The result could be sensitive slabs formed due to strong winds overnight or snow and moderate winds combining to build hazard throughout the day (or potentially both).

Prior to this wind event, the upper snowpack was thought to be generally right-side-up as convective snow showers and periods of sun breaks impacted the zone throughout much of the past week. However, weak surfaces were observed in recent days and larger (D2-2.5) avalanches were reported earlier this week. Some of these avalanches broke as much as 3 feet deep and were suspected to have failed on the 2/25 interface. Most of them were in wind-loaded terrain, with one slide a result of a smaller Wind Slab stepping down to this older layer. Snowpack tests on the 2/25 by NWAC forecasters this week have not been overly impressive, but we shouldn’t ignore these red flag signs heading into a loading event, even if they are a few days old. We suspect most avalanches on Friday will be confined to the newly fallen snow, but if you’re going to see a deeper slide, it will likely be on this interface. 

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