Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Kernpunkte

You may encounter fresh wind drifts and shallow wind slabs along ridgelines at higher elevations.  Depending on how the day plays out, small wet loose avalanches are possible on very steep sunny slopes. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Following a few inches of new snow and periods of moderate ridgeline winds, you'll likely encounter fresh but shallow wind slabs below ridgelines at upper elevations.  Steer around drifts on slopes steeper than 35 degrees.  Cracking in the new snow, blowing snow, sharp cornices, and wind-sculpted features are all indicators that you may trigger a wind slab avalanche on nearby slopes. 

    With only a few inches of new snow, it's unlikely wet loose avalanches will be a significant avalanche problem on Thursday.  However, it's springtime and we don't have a solid picture of how Wednesday's storm played out. Keep in mind that natural wet loose avalanches may occur on steep slopes below rocky terrain as the day warms and during sunbreaks.  If you see signs of pinwheels, rollerballs or natural wet loose avalanches, avoid very steep terrain features and pivot to cooler slopes and simpler terrain away from terrain traps.

    (2/27/2024)

    An example of a skier-triggered wind slab avalanche on February 27th. Fisher Peak, E, 6,900ft

    Photo: NCH

Avalanche Discussion

We're removing the persistent slab problem for the time being.  The structure still exists at upper elevations on northerly aspects but there haven't been observed avalanches or other indicators of instability for some time. Continue to keep dormant persistent weak layers in your mind as we move through the Spring and continue to limit your exposure to large, complex, and unsupported start zones at upper elevations. If you travel on northerly slopes at upper elevations, use snowpack tests to look for weak layers in the middle of the snowpack, 3-4 feet below the surface. These may show up as strong-over-weak layers or very thin, softer interfaces adjacent to a crust. The last known avalanches on deeper weak layers occurred around the middle of the month during a prolonged period of very warm temperatures. 

Following very warm weather in the middle of March, temperatures cooled. A refreezing upper snowpack (at least at middle and upper elevations) has minimized snowpack concerns for avalanches occurring below the surface snow. On sun-exposed slopes, you may find a new host of new crusts that added strength to the snowpack. Where the snowpack stayed mostly dry, you may be able to find a few older weak layers in the upper to middle of the snowpack. These include the March 9th strong-over-weak interface that's 1-2 feet below the surface. Also, the weak layers of February 25th, mid-February, and the January 31st crust can all be found within 1 foot of each other 2-4 feet below the surface.

A storm system on Wednesday looks like it largely spared the East North zone with weather stations only showing 2-3" of new snow at mid and upper elevations. 

Snowpack information is limited outside of the Highway 20 corridor and Harts Pass. Let us know what you find if you get out into the backcountry!

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