Lawinenlagebericht

West Slopes North

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

Kernpunkte

Anticipate a stormy morning with another round of snow and wind. Back off steep terrain when you start seeing signs of instability like shooting cracks. Steer away from slopes getting actively wind loaded. Avalanche danger should be greatest in the morning and lessen throughout the day.

Lawinenprobleme

  • Storm Slabs

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

    New and wind-drifted snow should initially have a poor bond with the weak, light, and dry snow it falls on. You are more likely to trigger an avalanche in terrain where the wind is building thicker slabs, but will likely find a denser layer of new snow over softer snow on any aspect.

    Monitor the bond of new snow layers using hand shears, test slopes, and stomping on wind-drifted features to check how well the new layers are bonding. Stay alert to signs of instability like whumping, shooting cracks, and recent natural or human-triggered avalanches. Plan on sticking to simple, sheltered terrain for the morning. Use good observations to gauge instability before moving into anything bigger as it gets less stormy.

    (3/11/2023)

    Dense snow falling on weaker snow could produce slab avalanches on Monday, even in more wind-protected areas.

    Photo: Pete Durr

Avalanche Discussion

The latest round of snowfall delivered 6-12” of dry new snow by Sunday morning. Lots of people were out in backcountry terrain and reports were similar - calmer weather and much less avalanche danger than the day prior. No human-triggered slab avalanches were reported as of Sunday afternoon, but loose dry avalanches were gaining enough mass to push some folks off their feet. 

With improved visibility, a few natural avalanches that released during Saturday’s storm were observed, but most were small and there just weren’t that many.  No big crowns or debris piles were reported from any sub-zone. Riding conditions were reported as quite good with fast, boot-top powder on top of yesterday’s supportable wind slab. Minimal wind effect was noted in the topmost layer of new snow. 

In the Baker BC, there is roughly 3' of snow over the 12/7 rain crust, while a NWAC Forecaster in Glacier Creek found about half that amount over the crust at 5000’. Snow profiles consistently produced resistant planar test results at weaker layers above the rain crust. Further investigation showed a small amount of faceting in some snowpits, but nothing to write home about. 

The only sign of lingering instability in deeper layers of snow was a large whump reported from a southerly aspect from above 5000’ in the Baker BC. This is a sign there is a more developed weak layer out there somewhere. But the lack of large natural avalanches during the storm - and human-triggered slab avalanches on Sunday - point towards the idea that big avalanches releasing in deeper layers of snow would likely be very isolated in distribution. 

Be ready to assess stability and find conditions different than expected. The diverse range of weather effects from the latest storms means the actual avalanche danger and the kind of avalanches you might find vary widely between different parts of the same forecast zone.

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