Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

Updated 4/10 at 06:15: New snow with very strong winds is creating dangerous avalanche conditions in alpine terrain near the Cascade crest, where snowfall is continuing through the morning. Avoid steep, wind-loaded slopes at upper elevations, where wind slabs could be close to 2ft thick. Identify and navigate around steep slopes if you find signs of instability such as shooting cracks, and strong over weak layering. Small wet loose avalanches could be triggered at lower elevations with daytime warming.

Lawinenprobleme

  • Wind Slabs

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

    A Puget Sound Convergence Zone is creating dangerous conditions in alpine terrain of the zone between I-90 and Hwy 2. Strong westerly winds will quickly transport the fresh low-density snow into thicker slabs at upper elevations. Monitor the amount of new snow over recent crusts as you travel. You are most likely to find these below ridgelines, in gullies, and on open slopes or beneath rock bands. Expect thicker slabs at upper elevations on leeward slopes (north to east to south). Slabs may break at the new snow/old snow interface, but above treeline and in prime loading locations they could step down to older layers and up to 2ft deep. Feel for stiffer snow and identify wind-textured surfaces or pillows of fresh snow. If you notice shooting cracks or any fresh avalanches, stay off slopes greater than 35 degrees.

    (4/9/2021) Cross loaded features on high, north-facing terrain in Whitepine Cirque speak to wind slab potential on those slopes.

  • Loose Wet

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

    Saturday looks like a cold and breezy day, but it's nearly mid-April, so expect some warming of snow surfaces. Loose wet avalanches could be triggered on slopes that receive direct sun. Feel for moistening snow surfaces, and watch for indicators of snow surfaces losing strength such as rollerballs. If this starts happening move to shadier slopes or lower angle terrain without steeper slopes above you. 

    (3/30/2021) A small, skier triggered wet loose avalanche on a southeast facing slope at 6,300ft near Mission Ridge. Photo: Matt Primomo

Avalanche Discussion

A cold spring storm with very strong winds looks to roll through on Friday night. Cold temperatures and strong wind will easily transport the new snow (4"-8") into drifts and slabs. On Friday, multiple skier triggered avalanches, including an involvement where a skier was caught and carried, occurred in the neighboring Snoqualmie Pass zone. This was over 2ft deep, and ran on a layer of graupel over the recent crust on a north aspect at 6,700ft. Textured and pillowed snow surfaces could be found on many upper elevation slopes, and small ski-triggered wind slabs were reported from the Chiwaukum Range. In Whitepine Cirque of nearby Stevens Pass, I found that wind slabs could be up to a foot thick and more likely to fracture on very steep or unsupported features. A wet loose avalanche cycle occurred east of Stevens Pass where more sun made it through the clouds, and the new snow slid easily over the recently buried crust. Avalanches ran on east to south to west aspects at all elevations, and large terrain features produced larger avalanches.

The new snow will be adding to the 4-8" of new snow that fell on 4/8. Lower snow totals in eastern portions of the zone may limit avalanche hazard in areas such as the Wenatchee Mountains. The lower snowpack is generally strong and well settled, although a layer of facets associated with a crust from mid-January can be found 2-6 feet below the surface. This layer has been dormant for about a month but it may awaken later this spring with the right conditions.  

If you're out this weekend, help us and the rest of the backcountry community keep up with the quickly changing spring conditions by submitting an observation here. 

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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