Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You can trigger avalanches in the recent storm snow at middle and upper elevations. These will mostly be smaller loose wet avalanches, though you may encounter drier snow on shaded slopes. The sun will warm the light snow that accumulates overnight and the 8" that fell this weekend.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    You can trigger wet avalanches on slopes steeper than 35 degrees, especially on sun-exposed slopes. Watch for signs of instability, like fresh avalanches and rollerballs, that indicate you could trigger an avalanche. Anticipate the chances of triggering avalanches and move to lower-angle slopes to avoid them.

    If you travel to upper-elevation terrain, you'll find dry snow on shaded, northerly aspects. Be on the lookout for shallow drifts and other signs of wind slab avalanches.

    (3/24/2024)

    Skiers triggered small wet avalanches in 20cm (8") of new storm snow on steep, sun-exposed slopes. 

    Kangaroo Pass, SSE, 6,600ft

    Photo: Will Govus

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    Until we can be more certain about the snowpack structure, continue to put a large buffer between where you travel and large, complex, and unsupported start zones at upper elevations.

    While triggering avalanches on deeper weak layers may be very difficult, information on the current snowpack structure is limited. 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. 

    (3/15/2024)

    This crown from Azurite Peak highlights the type of big, alpine terrain where the potential for very large human-triggered or cornice-triggered avalanches remains.

    Photo: Willie Webster

Avalanche Discussion

Expect another dusting of 1-2" with clearing and mostly light winds. Sun and warm temperatures have made it easy to trigger wet avalanches in the 8-10" of snow that fell at upper elevations on the 23rd. Observers reported triggering small wet avalanches on both Sunday and Monday.

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. That said, we have a lot of uncertainty about the snowpack structure as observations are limited. Be prepared to make your own assessments of the persistent slab problem. On sun-exposed slopes, you may find a new host of layers created by water pooling in the upper snowpack. As these freeze, they should be adding 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 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.

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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